* [RFC] [gdb/build] Require c++17 compiler
@ 2023-10-05 6:54 Tom de Vries
2023-10-05 10:33 ` [PATCH RFC] " Lancelot SIX
` (3 more replies)
0 siblings, 4 replies; 14+ messages in thread
From: Tom de Vries @ 2023-10-05 6:54 UTC (permalink / raw)
To: gdb-patches
Since gdb 8.0, we've required a c++11 compiler.
That allowed gdb to be compiled with gcc releases as far back as gcc 4.8,
using an explicit -std=c++11 to override the default.
[ Gcc has the following defaults:
- before gcc 6: c++98, and
- for gcc 6-10: c++14, and
- since gcc 11: c++17. ]
There are two arguments in favor of moving to requiring a newer c++ standard:
- benefits can be had from using newer c++ features. We're already using some
of those features using gdb-specific implementations.
- when developing gdb on modern platforms with system compiler gcc >= 6,
people can accidentally use c++14/c++17 features in a patch, only to find out
post-commit that it breaks the build on a system with a compiler that only
supports c++11, which is inconvenient and takes time to fix.
[ This could be partially mitigated by if possible also forcing -std=c++11
for such compilers. ]
The need to keep requiring c++11 comes from porting new gdb releases to older
systems with older system compilers.
A review of some relevant distros has shown that in case that requiring c++17
results in no longer being able to use the system compiler, an alternative,
newer compiler that does support c++17 is readily available.
With nothing holding back the change, require a c++17 compiler to build gdb.
The gcc documentation ( https://gcc.gnu.org/projects/cxx-status.html ) states
that "Some C++17 features are available since GCC 5, but support was
experimental and the ABI of C++17 features was not stable until GCC 9".
Consequently, the NEWS item mentions gcc 9 as an example compiler to use.
My understanding of using gcc 5-8 is that it works as long as gdb doesn't use
not yet available language features. Of course the set of used language
features may change in time, so what compiler still works may change.
Problems can arise when shared libs starts to have C++17 based APIs (or
somehow expose instantiations of such classes). If compiled with a compiler
in which c++17 support was still experimental, it may be incompatible when
linking with:
- code compiled with a compiler with non-experimental c++17 support, or
- code compiled with a different compiler with experimental c++17 support.
Looking at the current implementation of our only shared lib:
libinproctrace.so, I couldn't spot any c++ usage in the API, so I'm assuming
this problem is not likely to happen.
Requiring c++17 means we can drop some code:
...
$ find gdb* -type f \
| egrep -v "/configure|\.m4" \
| xargs grep "# *if.*__cplusplus.*2014"
gdb/cp-support.c:#if __cplusplus >= 201402L
gdb/dwarf2/cooked-index.c:#if __cplusplus >= 201402L
gdbsupport/gdb_optional.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
gdbsupport/gdb_optional.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
gdbsupport/gdb_unique_ptr.h:#if __cplusplus >= 201402L
gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
$ find gdb* -type f \
| egrep -v "/configure|\.m4" \
| xargs grep "# *if.*__cplusplus.*2017"
gdb/unittests/string_view-selftests.c:#if __cplusplus < 201703L
gdb/disasm.h:#if __cplusplus >= 201703L
gdbsupport/invoke-result.h:#if __cplusplus >= 201703L
gdbsupport/gdb_string_view.h:#if __cplusplus >= 201703L
...
but that's not yet included in this patch.
Tested on x86_64-linux.
---
gdb/NEWS | 3 +
gdb/configure | 2030 ++++++++++++++++++++++++++++++++++-----
gdb/configure.ac | 4 +-
gdbserver/configure | 2018 +++++++++++++++++++++++++++++++++-----
gdbserver/configure.ac | 4 +-
gdbsupport/configure | 2018 +++++++++++++++++++++++++++++++++-----
gdbsupport/configure.ac | 4 +-
7 files changed, 5391 insertions(+), 690 deletions(-)
diff --git a/gdb/NEWS b/gdb/NEWS
index fc4c7c01661..4c57de1c402 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,9 @@
*** Changes since GDB 13
+* Building GDB and GDBserver now requires a C++17 compiler.
+ For example, GCC 9 or later.
+
* GDB now supports the AArch64 Scalable Matrix Extension 2 (SME2), which
includes a new 512 bit lookup table register named ZT0.
diff --git a/gdb/configure b/gdb/configure
index 2d07e0cb596..3ef3ddf3475 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -803,7 +803,7 @@ CCDEPMODE
DEPDIR
am__leading_dot
CXX_DIALECT
-HAVE_CXX11
+HAVE_CXX17
CXXCPP
OTOOL64
OTOOL
@@ -16487,9 +16487,9 @@ exec 5>>config.log
$lt_cl_success || as_fn_exit 1
-# We require a C++11 compiler. Check if one is available, and if
+# We require a C++17 compiler. Check if one is available, and if
# necessary, set CXX_DIALECT to some -std=xxx switch.
- ax_cxx_compile_alternatives="11 0x" ax_cxx_compile_cxx11_required=true
+ ax_cxx_compile_alternatives="17 1z" ax_cxx_compile_cxx17_required=true
ac_ext=cpp
ac_cpp='$CXXCPP $CPPFLAGS'
ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -16497,9 +16497,9 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
CXX_DIALECT=""
ac_success=no
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
-$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
-if ${ax_cv_cxx_compile_cxx11+:} false; then :
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features by default" >&5
+$as_echo_n "checking whether $CXX supports C++17 features by default... " >&6; }
+if ${ax_cv_cxx_compile_cxx17+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -16790,355 +16790,554 @@ namespace cxx11
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
- ax_cv_cxx_compile_cxx11=yes
-else
- ax_cv_cxx_compile_cxx11=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
-$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
- if test x$ax_cv_cxx_compile_cxx11 = xyes; then
- ac_success=yes
- fi
-
- if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- switch="-std=gnu++${alternative}"
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
-if eval \${$cachevar+:} false; then :
- $as_echo_n "(cached) " >&6
-else
- ac_save_CXX="$CXX"
- CXX="$CXX $switch"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h. */
-
-// If the compiler admits that it is not ready for C++11, why torture it?
+// If the compiler admits that it is not ready for C++14, why torture it?
// Hopefully, this will speed up the test.
#ifndef __cplusplus
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+#elif __cplusplus < 201402L
-#error "This is not a C++11 compiler"
+#error "This is not a C++14 compiler"
#else
-namespace cxx11
+namespace cxx14
{
- namespace test_static_assert
+ namespace test_polymorphic_lambdas
{
- template <typename T>
- struct check
+ int
+ test()
{
- static_assert(sizeof(int) <= sizeof(T), "not big enough");
- };
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
}
- namespace test_final_override
+ namespace test_binary_literals
{
- struct Base
- {
- virtual void f() {}
- };
-
- struct Derived : public Base
- {
- virtual void f() override {}
- };
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
}
- namespace test_double_right_angle_brackets
+ namespace test_generalized_constexpr
{
- template < typename T >
- struct check {};
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
- typedef check<void> single_type;
- typedef check<check<void>> double_type;
- typedef check<check<check<void>>> triple_type;
- typedef check<check<check<check<void>>>> quadruple_type;
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
}
- namespace test_decltype
+ namespace test_lambda_init_capture
{
int
- f()
+ test()
{
- int a = 1;
- decltype(a) b = 2;
- return a + b;
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
}
}
- namespace test_type_deduction
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
{
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
template < typename T1, typename T2 >
struct is_same
{
- static const bool value = false;
+ static constexpr auto value = false;
};
template < typename T >
struct is_same<T, T>
{
- static const bool value = true;
+ static constexpr auto value = true;
};
- template < typename T1, typename T2 >
- auto
- add(T1 a1, T2 a2) -> decltype(a1 + a2)
- {
- return a1 + a2;
- }
-
int
- test(const int c, volatile int v)
+ test()
{
- static_assert(is_same<int, decltype(0)>::value == true, "");
- static_assert(is_same<int, decltype(c)>::value == false, "");
- static_assert(is_same<int, decltype(v)>::value == false, "");
- auto ac = c;
- auto av = v;
- auto sumi = ac + av + 'x';
- auto sumf = ac + av + 1.0;
- static_assert(is_same<int, decltype(ac)>::value == true, "");
- static_assert(is_same<int, decltype(av)>::value == true, "");
- static_assert(is_same<int, decltype(sumi)>::value == true, "");
- static_assert(is_same<int, decltype(sumf)>::value == false, "");
- static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
- return (sumf > 0.0) ? sumi : add(c, v);
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
}
}
- namespace test_noexcept
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus <= 201402L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
{
- int f() { return 0; }
- int g() noexcept { return 0; }
+ // TODO: test it with clang++ from git
- static_assert(noexcept(f()) == false, "");
- static_assert(noexcept(g()) == true, "");
+ constexpr int foo = [](){return 42;}();
}
+#endif // !defined(REALLY_CLANG)
- namespace test_constexpr
+ namespace test::nested_namespace::definitions
{
- template < typename CharT >
- unsigned long constexpr
- strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
{
- return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+ return (args * ... * 1);
}
- template < typename CharT >
- unsigned long constexpr
- strlen_c(const CharT *const s) noexcept
+ template<typename... Args>
+ bool all(Args... args)
{
- return strlen_c_r(s, 0UL);
+ return (args && ...);
}
- static_assert(strlen_c("") == 0UL, "");
- static_assert(strlen_c("1") == 1UL, "");
- static_assert(strlen_c("example") == 7UL, "");
- static_assert(strlen_c("another\0example") == 7UL, "");
-
}
- namespace test_rvalue_references
+ namespace test_extended_static_assert
{
- template < int N >
- struct answer
- {
- static constexpr int value = N;
- };
+ static_assert (true);
- answer<1> f(int&) { return answer<1>(); }
- answer<2> f(const int&) { return answer<2>(); }
- answer<3> f(int&&) { return answer<3>(); }
+ }
- void
- test()
- {
- int i = 0;
- const int c = 0;
- static_assert(decltype(f(i))::value == 1, "");
- static_assert(decltype(f(c))::value == 2, "");
- static_assert(decltype(f(0))::value == 3, "");
- }
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
}
- namespace test_uniform_initialization
+ namespace test_typename_in_template_template_parameter
{
- struct test
- {
- static const int zero {};
- static const int one {1};
- };
-
- static_assert(test::zero == 0, "");
- static_assert(test::one == 1, "");
+ template<template<typename> typename X> struct D;
}
- namespace test_lambdas
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
{
- void
- test1()
- {
- auto lambda1 = [](){};
- auto lambda2 = lambda1;
- lambda1();
- lambda2();
- }
-
- int
- test2()
+ int f1()
{
- auto a = [](int i, int j){ return i + j; }(1, 2);
- auto b = []() -> int { return '0'; }();
- auto c = [=](){ return a + b; }();
- auto d = [&](){ return c; }();
- auto e = [a, &b](int x) mutable {
- const auto identity = [](int y){ return y; };
- for (auto i = 0; i < a; ++i)
- a += b--;
- return x + identity(a + b);
- }(0);
- return a + b + c + d + e;
+ return 42;
}
- int
- test3()
+ [[nodiscard]] int f2()
{
- const auto nullary = [](){ return 0; };
- const auto unary = [](int x){ return x; };
- using nullary_t = decltype(nullary);
- using unary_t = decltype(unary);
- const auto higher1st = [](nullary_t f){ return f(); };
- const auto higher2nd = [unary](nullary_t f1){
- return [unary, f1](unary_t f2){ return f2(unary(f1())); };
- };
- return higher1st(nullary) + higher2nd(nullary)(unary);
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
}
}
- namespace test_variadic_templates
+ namespace test_extended_aggregate_initialization
{
- template <int...>
- struct sum;
+ struct base1
+ {
+ int b1, b2 = 42;
+ };
- template <int N0, int... N1toN>
- struct sum<N0, N1toN...>
+ struct base2
{
- static constexpr auto value = N0 + sum<N1toN...>::value;
+ base2() {
+ b3 = 42;
+ }
+ int b3;
};
- template <>
- struct sum<>
+ struct derived : base1, base2
{
- static constexpr auto value = 0;
+ int d;
};
- static_assert(sum<>::value == 0, "");
- static_assert(sum<1>::value == 1, "");
- static_assert(sum<23>::value == 23, "");
- static_assert(sum<1, 2>::value == 3, "");
- static_assert(sum<5, 5, 11>::value == 21, "");
- static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
}
- // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
- // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
- // because of this.
- namespace test_template_alias_sfinae
+ namespace test_general_range_based_for_loop
{
- struct foo {};
+ struct iter
+ {
+ int i;
- template<typename T>
- using member = typename T::member_type;
+ int& operator* ()
+ {
+ return i;
+ }
- template<typename T>
- void func(...) {}
+ const int& operator* () const
+ {
+ return i;
+ }
- template<typename T>
- void func(member<T>*) {}
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
- void test();
+ struct sentinel
+ {
+ int i;
+ };
- void test() { func<foo>(0); }
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
+ }
- }
+ bool operator!= (const iter& i, const sentinel& s)
+ {
+ return !(i == s);
+ }
-} // namespace cxx11
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
-#endif // __cplusplus >= 201103L
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+ void f()
+ {
+ range r {};
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
+ }
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
- eval $cachevar=yes
+ }
+
+ namespace test_lambda_capture_asterisk_this_by_value
+ {
+
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
+
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
+
+ }
+
+ namespace test_constexpr_if
+ {
+
+ template <bool cond>
+ int f ()
+ {
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
+ }
+
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
+ {
+ return 13;
+ }
+
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
+ {
+
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
+ {
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
+
+ T1 m1;
+ T2 m2;
+ };
+
+ void f()
+ {
+ [[maybe_unused]] auto p = pair{13, 42u};
+ }
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_non_type_auto_template_parameters
+ {
+
+ template <auto n>
+ struct B
+ {};
+
+ B<5> b1;
+ B<'a'> b2;
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
+ {
+
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
+ {
+ return arr;
+ }
+
+ auto f2() -> std::pair<int, int>&
+ {
+ return pr;
+ }
+
+ struct S
+ {
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
+ }
+
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
+ {
+
+ // TODO: test it with clang++ from git
+
+ struct Good {};
+ struct Bad {};
+
+ void g1() noexcept;
+ void g2();
+
+ template<typename T>
+ Bad
+ f(T*, T*);
+
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
+
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_inline_variables
+ {
+
+ template<class T> void f(T)
+ {}
+
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
+
+ template<> inline void f<>(int)
+ {}
+
+ template<> int g<>(int)
+ {
+ return 5;
+ }
+
+ }
+
+} // namespace cxx17
+
+#endif // __cplusplus <= 201402L
+
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ ax_cv_cxx_compile_cxx17=yes
else
- eval $cachevar=no
+ ax_cv_cxx_compile_cxx17=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
- CXX="$ac_save_CXX"
fi
-eval ac_res=\$$cachevar
- { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
- if eval test x\$$cachevar = xyes; then
- CXX_DIALECT="$switch"
- CXX="$CXX $switch"
- if test -n "$CXXCPP" ; then
- CXXCPP="$CXXCPP $switch"
- fi
- ac_success=yes
- break
- fi
- done
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx17" >&5
+$as_echo "$ax_cv_cxx_compile_cxx17" >&6; }
+ if test x$ax_cv_cxx_compile_cxx17 = xyes; then
+ ac_success=yes
fi
if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ switch="-std=gnu++${alternative}"
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
if eval \${$cachevar+:} false; then :
$as_echo_n "(cached) " >&6
else
ac_save_CXX="$CXX"
- CXX="$CXX $switch"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ CXX="$CXX $switch"
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
@@ -17426,6 +17625,1373 @@ namespace cxx11
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+ namespace test_polymorphic_lambdas
+ {
+
+ int
+ test()
+ {
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
+
+ }
+
+ namespace test_binary_literals
+ {
+
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
+
+ }
+
+ namespace test_generalized_constexpr
+ {
+
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
+
+ }
+
+ namespace test_lambda_init_capture
+ {
+
+ int
+ test()
+ {
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
+ }
+
+ }
+
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
+ {
+
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static constexpr auto value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus <= 201402L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
+ {
+
+ // TODO: test it with clang++ from git
+
+ constexpr int foo = [](){return 42;}();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test::nested_namespace::definitions
+ {
+
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
+ {
+ return (args * ... * 1);
+ }
+
+ template<typename... Args>
+ bool all(Args... args)
+ {
+ return (args && ...);
+ }
+
+ }
+
+ namespace test_extended_static_assert
+ {
+
+ static_assert (true);
+
+ }
+
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
+ }
+
+ namespace test_typename_in_template_template_parameter
+ {
+
+ template<template<typename> typename X> struct D;
+
+ }
+
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
+ {
+
+ int f1()
+ {
+ return 42;
+ }
+
+ [[nodiscard]] int f2()
+ {
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
+ }
+
+ }
+
+ namespace test_extended_aggregate_initialization
+ {
+
+ struct base1
+ {
+ int b1, b2 = 42;
+ };
+
+ struct base2
+ {
+ base2() {
+ b3 = 42;
+ }
+ int b3;
+ };
+
+ struct derived : base1, base2
+ {
+ int d;
+ };
+
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
+
+ }
+
+ namespace test_general_range_based_for_loop
+ {
+
+ struct iter
+ {
+ int i;
+
+ int& operator* ()
+ {
+ return i;
+ }
+
+ const int& operator* () const
+ {
+ return i;
+ }
+
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
+
+ struct sentinel
+ {
+ int i;
+ };
+
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
+ }
+
+ bool operator!= (const iter& i, const sentinel& s)
+ {
+ return !(i == s);
+ }
+
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
+
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+
+ void f()
+ {
+ range r {};
+
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
+ }
+
+ }
+
+ namespace test_lambda_capture_asterisk_this_by_value
+ {
+
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
+
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
+
+ }
+
+ namespace test_constexpr_if
+ {
+
+ template <bool cond>
+ int f ()
+ {
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
+ }
+
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
+ {
+ return 13;
+ }
+
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
+ {
+
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
+ {
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
+
+ T1 m1;
+ T2 m2;
+ };
+
+ void f()
+ {
+ [[maybe_unused]] auto p = pair{13, 42u};
+ }
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_non_type_auto_template_parameters
+ {
+
+ template <auto n>
+ struct B
+ {};
+
+ B<5> b1;
+ B<'a'> b2;
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
+ {
+
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
+ {
+ return arr;
+ }
+
+ auto f2() -> std::pair<int, int>&
+ {
+ return pr;
+ }
+
+ struct S
+ {
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
+ }
+
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
+ {
+
+ // TODO: test it with clang++ from git
+
+ struct Good {};
+ struct Bad {};
+
+ void g1() noexcept;
+ void g2();
+
+ template<typename T>
+ Bad
+ f(T*, T*);
+
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
+
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_inline_variables
+ {
+
+ template<class T> void f(T)
+ {}
+
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
+
+ template<> inline void f<>(int)
+ {}
+
+ template<> int g<>(int)
+ {
+ return 5;
+ }
+
+ }
+
+} // namespace cxx17
+
+#endif // __cplusplus <= 201402L
+
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ eval $cachevar=yes
+else
+ eval $cachevar=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ CXX="$ac_save_CXX"
+fi
+eval ac_res=\$$cachevar
+ { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+ if eval test x\$$cachevar = xyes; then
+ CXX_DIALECT="$switch"
+ CXX="$CXX $switch"
+ if test -n "$CXXCPP" ; then
+ CXXCPP="$CXXCPP $switch"
+ fi
+ ac_success=yes
+ break
+ fi
+ done
+ fi
+
+ if test x$ac_success = xno; then
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
+if eval \${$cachevar+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ ac_save_CXX="$CXX"
+ CXX="$CXX $switch"
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+
+// If the compiler admits that it is not ready for C++11, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201103L
+
+#error "This is not a C++11 compiler"
+
+#else
+
+namespace cxx11
+{
+
+ namespace test_static_assert
+ {
+
+ template <typename T>
+ struct check
+ {
+ static_assert(sizeof(int) <= sizeof(T), "not big enough");
+ };
+
+ }
+
+ namespace test_final_override
+ {
+
+ struct Base
+ {
+ virtual void f() {}
+ };
+
+ struct Derived : public Base
+ {
+ virtual void f() override {}
+ };
+
+ }
+
+ namespace test_double_right_angle_brackets
+ {
+
+ template < typename T >
+ struct check {};
+
+ typedef check<void> single_type;
+ typedef check<check<void>> double_type;
+ typedef check<check<check<void>>> triple_type;
+ typedef check<check<check<check<void>>>> quadruple_type;
+
+ }
+
+ namespace test_decltype
+ {
+
+ int
+ f()
+ {
+ int a = 1;
+ decltype(a) b = 2;
+ return a + b;
+ }
+
+ }
+
+ namespace test_type_deduction
+ {
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static const bool value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static const bool value = true;
+ };
+
+ template < typename T1, typename T2 >
+ auto
+ add(T1 a1, T2 a2) -> decltype(a1 + a2)
+ {
+ return a1 + a2;
+ }
+
+ int
+ test(const int c, volatile int v)
+ {
+ static_assert(is_same<int, decltype(0)>::value == true, "");
+ static_assert(is_same<int, decltype(c)>::value == false, "");
+ static_assert(is_same<int, decltype(v)>::value == false, "");
+ auto ac = c;
+ auto av = v;
+ auto sumi = ac + av + 'x';
+ auto sumf = ac + av + 1.0;
+ static_assert(is_same<int, decltype(ac)>::value == true, "");
+ static_assert(is_same<int, decltype(av)>::value == true, "");
+ static_assert(is_same<int, decltype(sumi)>::value == true, "");
+ static_assert(is_same<int, decltype(sumf)>::value == false, "");
+ static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
+ return (sumf > 0.0) ? sumi : add(c, v);
+ }
+
+ }
+
+ namespace test_noexcept
+ {
+
+ int f() { return 0; }
+ int g() noexcept { return 0; }
+
+ static_assert(noexcept(f()) == false, "");
+ static_assert(noexcept(g()) == true, "");
+
+ }
+
+ namespace test_constexpr
+ {
+
+ template < typename CharT >
+ unsigned long constexpr
+ strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+ {
+ return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+ }
+
+ template < typename CharT >
+ unsigned long constexpr
+ strlen_c(const CharT *const s) noexcept
+ {
+ return strlen_c_r(s, 0UL);
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("1") == 1UL, "");
+ static_assert(strlen_c("example") == 7UL, "");
+ static_assert(strlen_c("another\0example") == 7UL, "");
+
+ }
+
+ namespace test_rvalue_references
+ {
+
+ template < int N >
+ struct answer
+ {
+ static constexpr int value = N;
+ };
+
+ answer<1> f(int&) { return answer<1>(); }
+ answer<2> f(const int&) { return answer<2>(); }
+ answer<3> f(int&&) { return answer<3>(); }
+
+ void
+ test()
+ {
+ int i = 0;
+ const int c = 0;
+ static_assert(decltype(f(i))::value == 1, "");
+ static_assert(decltype(f(c))::value == 2, "");
+ static_assert(decltype(f(0))::value == 3, "");
+ }
+
+ }
+
+ namespace test_uniform_initialization
+ {
+
+ struct test
+ {
+ static const int zero {};
+ static const int one {1};
+ };
+
+ static_assert(test::zero == 0, "");
+ static_assert(test::one == 1, "");
+
+ }
+
+ namespace test_lambdas
+ {
+
+ void
+ test1()
+ {
+ auto lambda1 = [](){};
+ auto lambda2 = lambda1;
+ lambda1();
+ lambda2();
+ }
+
+ int
+ test2()
+ {
+ auto a = [](int i, int j){ return i + j; }(1, 2);
+ auto b = []() -> int { return '0'; }();
+ auto c = [=](){ return a + b; }();
+ auto d = [&](){ return c; }();
+ auto e = [a, &b](int x) mutable {
+ const auto identity = [](int y){ return y; };
+ for (auto i = 0; i < a; ++i)
+ a += b--;
+ return x + identity(a + b);
+ }(0);
+ return a + b + c + d + e;
+ }
+
+ int
+ test3()
+ {
+ const auto nullary = [](){ return 0; };
+ const auto unary = [](int x){ return x; };
+ using nullary_t = decltype(nullary);
+ using unary_t = decltype(unary);
+ const auto higher1st = [](nullary_t f){ return f(); };
+ const auto higher2nd = [unary](nullary_t f1){
+ return [unary, f1](unary_t f2){ return f2(unary(f1())); };
+ };
+ return higher1st(nullary) + higher2nd(nullary)(unary);
+ }
+
+ }
+
+ namespace test_variadic_templates
+ {
+
+ template <int...>
+ struct sum;
+
+ template <int N0, int... N1toN>
+ struct sum<N0, N1toN...>
+ {
+ static constexpr auto value = N0 + sum<N1toN...>::value;
+ };
+
+ template <>
+ struct sum<>
+ {
+ static constexpr auto value = 0;
+ };
+
+ static_assert(sum<>::value == 0, "");
+ static_assert(sum<1>::value == 1, "");
+ static_assert(sum<23>::value == 23, "");
+ static_assert(sum<1, 2>::value == 3, "");
+ static_assert(sum<5, 5, 11>::value == 21, "");
+ static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+
+ }
+
+ // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+ // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
+ // because of this.
+ namespace test_template_alias_sfinae
+ {
+
+ struct foo {};
+
+ template<typename T>
+ using member = typename T::member_type;
+
+ template<typename T>
+ void func(...) {}
+
+ template<typename T>
+ void func(member<T>*) {}
+
+ void test();
+
+ void test() { func<foo>(0); }
+
+ }
+
+} // namespace cxx11
+
+#endif // __cplusplus >= 201103L
+
+
+
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+ namespace test_polymorphic_lambdas
+ {
+
+ int
+ test()
+ {
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
+
+ }
+
+ namespace test_binary_literals
+ {
+
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
+
+ }
+
+ namespace test_generalized_constexpr
+ {
+
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
+
+ }
+
+ namespace test_lambda_init_capture
+ {
+
+ int
+ test()
+ {
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
+ }
+
+ }
+
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
+ {
+
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static constexpr auto value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus <= 201402L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
+ {
+
+ // TODO: test it with clang++ from git
+
+ constexpr int foo = [](){return 42;}();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test::nested_namespace::definitions
+ {
+
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
+ {
+ return (args * ... * 1);
+ }
+
+ template<typename... Args>
+ bool all(Args... args)
+ {
+ return (args && ...);
+ }
+
+ }
+
+ namespace test_extended_static_assert
+ {
+
+ static_assert (true);
+
+ }
+
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
+ }
+
+ namespace test_typename_in_template_template_parameter
+ {
+
+ template<template<typename> typename X> struct D;
+
+ }
+
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
+ {
+
+ int f1()
+ {
+ return 42;
+ }
+
+ [[nodiscard]] int f2()
+ {
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
+ }
+
+ }
+
+ namespace test_extended_aggregate_initialization
+ {
+
+ struct base1
+ {
+ int b1, b2 = 42;
+ };
+
+ struct base2
+ {
+ base2() {
+ b3 = 42;
+ }
+ int b3;
+ };
+
+ struct derived : base1, base2
+ {
+ int d;
+ };
+
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
+
+ }
+
+ namespace test_general_range_based_for_loop
+ {
+
+ struct iter
+ {
+ int i;
+
+ int& operator* ()
+ {
+ return i;
+ }
+
+ const int& operator* () const
+ {
+ return i;
+ }
+
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
+
+ struct sentinel
+ {
+ int i;
+ };
+
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
+ }
+
+ bool operator!= (const iter& i, const sentinel& s)
+ {
+ return !(i == s);
+ }
+
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
+
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+
+ void f()
+ {
+ range r {};
+
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
+ }
+
+ }
+
+ namespace test_lambda_capture_asterisk_this_by_value
+ {
+
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
+
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
+
+ }
+
+ namespace test_constexpr_if
+ {
+
+ template <bool cond>
+ int f ()
+ {
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
+ }
+
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
+ {
+ return 13;
+ }
+
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
+ {
+
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
+ {
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
+
+ T1 m1;
+ T2 m2;
+ };
+
+ void f()
+ {
+ [[maybe_unused]] auto p = pair{13, 42u};
+ }
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_non_type_auto_template_parameters
+ {
+
+ template <auto n>
+ struct B
+ {};
+
+ B<5> b1;
+ B<'a'> b2;
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
+ {
+
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
+ {
+ return arr;
+ }
+
+ auto f2() -> std::pair<int, int>&
+ {
+ return pr;
+ }
+
+ struct S
+ {
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
+ }
+
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
+ {
+
+ // TODO: test it with clang++ from git
+
+ struct Good {};
+ struct Bad {};
+
+ void g1() noexcept;
+ void g2();
+
+ template<typename T>
+ Bad
+ f(T*, T*);
+
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
+
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_inline_variables
+ {
+
+ template<class T> void f(T)
+ {}
+
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
+
+ template<> inline void f<>(int)
+ {}
+
+ template<> int g<>(int)
+ {
+ return 5;
+ }
+
+ }
+
+} // namespace cxx17
+
+#endif // __cplusplus <= 201402L
+
+
+
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
eval $cachevar=yes
@@ -17459,19 +19025,19 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_c_compiler_gnu
- if test x$ax_cxx_compile_cxx11_required = xtrue; then
+ if test x$ax_cxx_compile_cxx17_required = xtrue; then
if test x$ac_success = xno; then
- as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5
+ as_fn_error $? "*** A compiler with support for C++17 language features is required." "$LINENO" 5
fi
fi
if test x$ac_success = xno; then
- HAVE_CXX11=0
- { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5
-$as_echo "$as_me: No compiler with C++11 support was found" >&6;}
+ HAVE_CXX17=0
+ { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++17 support was found" >&5
+$as_echo "$as_me: No compiler with C++17 support was found" >&6;}
else
- HAVE_CXX11=1
+ HAVE_CXX17=1
-$as_echo "#define HAVE_CXX11 1" >>confdefs.h
+$as_echo "#define HAVE_CXX17 1" >>confdefs.h
fi
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 97c6bf0ed5f..bcedd6d6584 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -53,9 +53,9 @@ LT_INIT
# link tests in the configure script.
LT_OUTPUT
-# We require a C++11 compiler. Check if one is available, and if
+# We require a C++17 compiler. Check if one is available, and if
# necessary, set CXX_DIALECT to some -std=xxx switch.
-AX_CXX_COMPILE_STDCXX(11, , mandatory)
+AX_CXX_COMPILE_STDCXX(17, , mandatory)
# Dependency checking.
ZW_CREATE_DEPDIR
diff --git a/gdbserver/configure b/gdbserver/configure
index e807c60c08a..28c78082b82 100755
--- a/gdbserver/configure
+++ b/gdbserver/configure
@@ -669,7 +669,7 @@ ax_pthread_config
SED
ALLOCA
CXX_DIALECT
-HAVE_CXX11
+HAVE_CXX17
RANLIB
AR
INSTALL_DATA
@@ -5007,10 +5007,10 @@ ac_script='s/[\\$]/&&/g;s/;s,x,x,$//'
program_transform_name=`$as_echo "$program_transform_name" | sed "$ac_script"`
-# We require a C++11 compiler. Check if one is available, and if
+# We require a C++17 compiler. Check if one is available, and if
# necessary, set CXX_DIALECT to some -std=xxx switch.
- ax_cxx_compile_alternatives="11 0x" ax_cxx_compile_cxx11_required=true
+ ax_cxx_compile_alternatives="17 1z" ax_cxx_compile_cxx17_required=true
ac_ext=cpp
ac_cpp='$CXXCPP $CPPFLAGS'
ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -5018,9 +5018,9 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
CXX_DIALECT=""
ac_success=no
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
-$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
-if ${ax_cv_cxx_compile_cxx11+:} false; then :
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features by default" >&5
+$as_echo_n "checking whether $CXX supports C++17 features by default... " >&6; }
+if ${ax_cv_cxx_compile_cxx17+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -5311,32 +5311,1399 @@ namespace cxx11
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+ namespace test_polymorphic_lambdas
+ {
+
+ int
+ test()
+ {
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
+
+ }
+
+ namespace test_binary_literals
+ {
+
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
+
+ }
+
+ namespace test_generalized_constexpr
+ {
+
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
+
+ }
+
+ namespace test_lambda_init_capture
+ {
+
+ int
+ test()
+ {
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
+ }
+
+ }
+
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
+ {
+
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static constexpr auto value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus <= 201402L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
+ {
+
+ // TODO: test it with clang++ from git
+
+ constexpr int foo = [](){return 42;}();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test::nested_namespace::definitions
+ {
+
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
+ {
+ return (args * ... * 1);
+ }
+
+ template<typename... Args>
+ bool all(Args... args)
+ {
+ return (args && ...);
+ }
+
+ }
+
+ namespace test_extended_static_assert
+ {
+
+ static_assert (true);
+
+ }
+
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
+ }
+
+ namespace test_typename_in_template_template_parameter
+ {
+
+ template<template<typename> typename X> struct D;
+
+ }
+
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
+ {
+
+ int f1()
+ {
+ return 42;
+ }
+
+ [[nodiscard]] int f2()
+ {
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
+ }
+
+ }
+
+ namespace test_extended_aggregate_initialization
+ {
+
+ struct base1
+ {
+ int b1, b2 = 42;
+ };
+
+ struct base2
+ {
+ base2() {
+ b3 = 42;
+ }
+ int b3;
+ };
+
+ struct derived : base1, base2
+ {
+ int d;
+ };
+
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
+
+ }
+
+ namespace test_general_range_based_for_loop
+ {
+
+ struct iter
+ {
+ int i;
+
+ int& operator* ()
+ {
+ return i;
+ }
+
+ const int& operator* () const
+ {
+ return i;
+ }
+
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
+
+ struct sentinel
+ {
+ int i;
+ };
+
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
+ }
+
+ bool operator!= (const iter& i, const sentinel& s)
+ {
+ return !(i == s);
+ }
+
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
+
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+
+ void f()
+ {
+ range r {};
+
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
+ }
+
+ }
+
+ namespace test_lambda_capture_asterisk_this_by_value
+ {
+
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
+
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
+
+ }
+
+ namespace test_constexpr_if
+ {
+
+ template <bool cond>
+ int f ()
+ {
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
+ }
+
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
+ {
+ return 13;
+ }
+
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
+ {
+
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
+ {
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
+
+ T1 m1;
+ T2 m2;
+ };
+
+ void f()
+ {
+ [[maybe_unused]] auto p = pair{13, 42u};
+ }
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_non_type_auto_template_parameters
+ {
+
+ template <auto n>
+ struct B
+ {};
+
+ B<5> b1;
+ B<'a'> b2;
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
+ {
+
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
+ {
+ return arr;
+ }
+
+ auto f2() -> std::pair<int, int>&
+ {
+ return pr;
+ }
+
+ struct S
+ {
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
+ }
+
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
+ {
+
+ // TODO: test it with clang++ from git
+
+ struct Good {};
+ struct Bad {};
+
+ void g1() noexcept;
+ void g2();
+
+ template<typename T>
+ Bad
+ f(T*, T*);
+
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
+
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_inline_variables
+ {
+
+ template<class T> void f(T)
+ {}
+
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
+
+ template<> inline void f<>(int)
+ {}
+
+ template<> int g<>(int)
+ {
+ return 5;
+ }
+
+ }
+
+} // namespace cxx17
+
+#endif // __cplusplus <= 201402L
+
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ ax_cv_cxx_compile_cxx17=yes
+else
+ ax_cv_cxx_compile_cxx17=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx17" >&5
+$as_echo "$ax_cv_cxx_compile_cxx17" >&6; }
+ if test x$ax_cv_cxx_compile_cxx17 = xyes; then
+ ac_success=yes
+ fi
+
+ if test x$ac_success = xno; then
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ switch="-std=gnu++${alternative}"
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
+if eval \${$cachevar+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ ac_save_CXX="$CXX"
+ CXX="$CXX $switch"
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+
+// If the compiler admits that it is not ready for C++11, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201103L
+
+#error "This is not a C++11 compiler"
+
+#else
+
+namespace cxx11
+{
+
+ namespace test_static_assert
+ {
+
+ template <typename T>
+ struct check
+ {
+ static_assert(sizeof(int) <= sizeof(T), "not big enough");
+ };
+
+ }
+
+ namespace test_final_override
+ {
+
+ struct Base
+ {
+ virtual void f() {}
+ };
+
+ struct Derived : public Base
+ {
+ virtual void f() override {}
+ };
+
+ }
+
+ namespace test_double_right_angle_brackets
+ {
+
+ template < typename T >
+ struct check {};
+
+ typedef check<void> single_type;
+ typedef check<check<void>> double_type;
+ typedef check<check<check<void>>> triple_type;
+ typedef check<check<check<check<void>>>> quadruple_type;
+
+ }
+
+ namespace test_decltype
+ {
+
+ int
+ f()
+ {
+ int a = 1;
+ decltype(a) b = 2;
+ return a + b;
+ }
+
+ }
+
+ namespace test_type_deduction
+ {
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static const bool value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static const bool value = true;
+ };
+
+ template < typename T1, typename T2 >
+ auto
+ add(T1 a1, T2 a2) -> decltype(a1 + a2)
+ {
+ return a1 + a2;
+ }
+
+ int
+ test(const int c, volatile int v)
+ {
+ static_assert(is_same<int, decltype(0)>::value == true, "");
+ static_assert(is_same<int, decltype(c)>::value == false, "");
+ static_assert(is_same<int, decltype(v)>::value == false, "");
+ auto ac = c;
+ auto av = v;
+ auto sumi = ac + av + 'x';
+ auto sumf = ac + av + 1.0;
+ static_assert(is_same<int, decltype(ac)>::value == true, "");
+ static_assert(is_same<int, decltype(av)>::value == true, "");
+ static_assert(is_same<int, decltype(sumi)>::value == true, "");
+ static_assert(is_same<int, decltype(sumf)>::value == false, "");
+ static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
+ return (sumf > 0.0) ? sumi : add(c, v);
+ }
+
+ }
+
+ namespace test_noexcept
+ {
+
+ int f() { return 0; }
+ int g() noexcept { return 0; }
+
+ static_assert(noexcept(f()) == false, "");
+ static_assert(noexcept(g()) == true, "");
+
+ }
+
+ namespace test_constexpr
+ {
+
+ template < typename CharT >
+ unsigned long constexpr
+ strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+ {
+ return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+ }
+
+ template < typename CharT >
+ unsigned long constexpr
+ strlen_c(const CharT *const s) noexcept
+ {
+ return strlen_c_r(s, 0UL);
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("1") == 1UL, "");
+ static_assert(strlen_c("example") == 7UL, "");
+ static_assert(strlen_c("another\0example") == 7UL, "");
+
+ }
+
+ namespace test_rvalue_references
+ {
+
+ template < int N >
+ struct answer
+ {
+ static constexpr int value = N;
+ };
+
+ answer<1> f(int&) { return answer<1>(); }
+ answer<2> f(const int&) { return answer<2>(); }
+ answer<3> f(int&&) { return answer<3>(); }
+
+ void
+ test()
+ {
+ int i = 0;
+ const int c = 0;
+ static_assert(decltype(f(i))::value == 1, "");
+ static_assert(decltype(f(c))::value == 2, "");
+ static_assert(decltype(f(0))::value == 3, "");
+ }
+
+ }
+
+ namespace test_uniform_initialization
+ {
+
+ struct test
+ {
+ static const int zero {};
+ static const int one {1};
+ };
+
+ static_assert(test::zero == 0, "");
+ static_assert(test::one == 1, "");
+
+ }
+
+ namespace test_lambdas
+ {
+
+ void
+ test1()
+ {
+ auto lambda1 = [](){};
+ auto lambda2 = lambda1;
+ lambda1();
+ lambda2();
+ }
+
+ int
+ test2()
+ {
+ auto a = [](int i, int j){ return i + j; }(1, 2);
+ auto b = []() -> int { return '0'; }();
+ auto c = [=](){ return a + b; }();
+ auto d = [&](){ return c; }();
+ auto e = [a, &b](int x) mutable {
+ const auto identity = [](int y){ return y; };
+ for (auto i = 0; i < a; ++i)
+ a += b--;
+ return x + identity(a + b);
+ }(0);
+ return a + b + c + d + e;
+ }
+
+ int
+ test3()
+ {
+ const auto nullary = [](){ return 0; };
+ const auto unary = [](int x){ return x; };
+ using nullary_t = decltype(nullary);
+ using unary_t = decltype(unary);
+ const auto higher1st = [](nullary_t f){ return f(); };
+ const auto higher2nd = [unary](nullary_t f1){
+ return [unary, f1](unary_t f2){ return f2(unary(f1())); };
+ };
+ return higher1st(nullary) + higher2nd(nullary)(unary);
+ }
+
+ }
+
+ namespace test_variadic_templates
+ {
+
+ template <int...>
+ struct sum;
+
+ template <int N0, int... N1toN>
+ struct sum<N0, N1toN...>
+ {
+ static constexpr auto value = N0 + sum<N1toN...>::value;
+ };
+
+ template <>
+ struct sum<>
+ {
+ static constexpr auto value = 0;
+ };
+
+ static_assert(sum<>::value == 0, "");
+ static_assert(sum<1>::value == 1, "");
+ static_assert(sum<23>::value == 23, "");
+ static_assert(sum<1, 2>::value == 3, "");
+ static_assert(sum<5, 5, 11>::value == 21, "");
+ static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+
+ }
+
+ // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+ // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
+ // because of this.
+ namespace test_template_alias_sfinae
+ {
+
+ struct foo {};
+
+ template<typename T>
+ using member = typename T::member_type;
+
+ template<typename T>
+ void func(...) {}
+
+ template<typename T>
+ void func(member<T>*) {}
+
+ void test();
+
+ void test() { func<foo>(0); }
+
+ }
+
+} // namespace cxx11
+
+#endif // __cplusplus >= 201103L
+
+
+
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+ namespace test_polymorphic_lambdas
+ {
+
+ int
+ test()
+ {
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
+
+ }
+
+ namespace test_binary_literals
+ {
+
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
+
+ }
+
+ namespace test_generalized_constexpr
+ {
+
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
+
+ }
+
+ namespace test_lambda_init_capture
+ {
+
+ int
+ test()
+ {
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
+ }
+
+ }
+
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
+ {
+
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static constexpr auto value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus <= 201402L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
+ {
+
+ // TODO: test it with clang++ from git
+
+ constexpr int foo = [](){return 42;}();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test::nested_namespace::definitions
+ {
+
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
+ {
+ return (args * ... * 1);
+ }
+
+ template<typename... Args>
+ bool all(Args... args)
+ {
+ return (args && ...);
+ }
+
+ }
+
+ namespace test_extended_static_assert
+ {
+
+ static_assert (true);
+
+ }
+
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
+ }
+
+ namespace test_typename_in_template_template_parameter
+ {
+
+ template<template<typename> typename X> struct D;
+
+ }
+
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
+ {
+
+ int f1()
+ {
+ return 42;
+ }
+
+ [[nodiscard]] int f2()
+ {
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
+ }
+
+ }
+
+ namespace test_extended_aggregate_initialization
+ {
+
+ struct base1
+ {
+ int b1, b2 = 42;
+ };
+
+ struct base2
+ {
+ base2() {
+ b3 = 42;
+ }
+ int b3;
+ };
+
+ struct derived : base1, base2
+ {
+ int d;
+ };
+
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
+
+ }
+
+ namespace test_general_range_based_for_loop
+ {
+
+ struct iter
+ {
+ int i;
+
+ int& operator* ()
+ {
+ return i;
+ }
+
+ const int& operator* () const
+ {
+ return i;
+ }
+
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
+
+ struct sentinel
+ {
+ int i;
+ };
+
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
+ }
+
+ bool operator!= (const iter& i, const sentinel& s)
+ {
+ return !(i == s);
+ }
+
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
+
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+
+ void f()
+ {
+ range r {};
+
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
+ }
+
+ }
+
+ namespace test_lambda_capture_asterisk_this_by_value
+ {
+
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
+
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
+
+ }
+
+ namespace test_constexpr_if
+ {
+
+ template <bool cond>
+ int f ()
+ {
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
+ }
+
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
+ {
+ return 13;
+ }
+
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
+ {
+
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
+ {
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
+
+ T1 m1;
+ T2 m2;
+ };
+
+ void f()
+ {
+ [[maybe_unused]] auto p = pair{13, 42u};
+ }
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_non_type_auto_template_parameters
+ {
+
+ template <auto n>
+ struct B
+ {};
+
+ B<5> b1;
+ B<'a'> b2;
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
+ {
+
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
+ {
+ return arr;
+ }
+
+ auto f2() -> std::pair<int, int>&
+ {
+ return pr;
+ }
+
+ struct S
+ {
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
+ }
+
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
+ {
+
+ // TODO: test it with clang++ from git
+
+ struct Good {};
+ struct Bad {};
+
+ void g1() noexcept;
+ void g2();
+
+ template<typename T>
+ Bad
+ f(T*, T*);
+
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
+
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_inline_variables
+ {
+
+ template<class T> void f(T)
+ {}
+
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
+
+ template<> inline void f<>(int)
+ {}
+
+ template<> int g<>(int)
+ {
+ return 5;
+ }
+
+ }
+
+} // namespace cxx17
+
+#endif // __cplusplus <= 201402L
+
+
+
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
- ax_cv_cxx_compile_cxx11=yes
+ eval $cachevar=yes
else
- ax_cv_cxx_compile_cxx11=no
+ eval $cachevar=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ CXX="$ac_save_CXX"
fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
-$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
- if test x$ax_cv_cxx_compile_cxx11 = xyes; then
- ac_success=yes
+eval ac_res=\$$cachevar
+ { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+ if eval test x\$$cachevar = xyes; then
+ CXX_DIALECT="$switch"
+ CXX="$CXX $switch"
+ if test -n "$CXXCPP" ; then
+ CXXCPP="$CXXCPP $switch"
+ fi
+ ac_success=yes
+ break
+ fi
+ done
fi
if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- switch="-std=gnu++${alternative}"
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
if eval \${$cachevar+:} false; then :
$as_echo_n "(cached) " >&6
else
ac_save_CXX="$CXX"
- CXX="$CXX $switch"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ CXX="$CXX $switch"
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
@@ -5624,326 +6991,525 @@ namespace cxx11
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
- eval $cachevar=yes
-else
- eval $cachevar=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
- CXX="$ac_save_CXX"
-fi
-eval ac_res=\$$cachevar
- { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
- if eval test x\$$cachevar = xyes; then
- CXX_DIALECT="$switch"
- CXX="$CXX $switch"
- if test -n "$CXXCPP" ; then
- CXXCPP="$CXXCPP $switch"
- fi
- ac_success=yes
- break
- fi
- done
- fi
- if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
-if eval \${$cachevar+:} false; then :
- $as_echo_n "(cached) " >&6
-else
- ac_save_CXX="$CXX"
- CXX="$CXX $switch"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h. */
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+ namespace test_polymorphic_lambdas
+ {
+
+ int
+ test()
+ {
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
+
+ }
+
+ namespace test_binary_literals
+ {
+
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
+
+ }
+
+ namespace test_generalized_constexpr
+ {
+
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
+
+ }
+
+ namespace test_lambda_init_capture
+ {
+
+ int
+ test()
+ {
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
+ }
+
+ }
+
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
+ {
+
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static constexpr auto value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+} // namespace cxx14
-// If the compiler admits that it is not ready for C++11, why torture it?
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
// Hopefully, this will speed up the test.
#ifndef __cplusplus
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+#elif __cplusplus <= 201402L
-#error "This is not a C++11 compiler"
+#error "This is not a C++17 compiler"
#else
-namespace cxx11
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
{
- namespace test_static_assert
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
{
- template <typename T>
- struct check
- {
- static_assert(sizeof(int) <= sizeof(T), "not big enough");
- };
+ // TODO: test it with clang++ from git
+
+ constexpr int foo = [](){return 42;}();
}
+#endif // !defined(REALLY_CLANG)
- namespace test_final_override
+ namespace test::nested_namespace::definitions
{
- struct Base
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
{
- virtual void f() {}
- };
+ return (args * ... * 1);
+ }
- struct Derived : public Base
+ template<typename... Args>
+ bool all(Args... args)
{
- virtual void f() override {}
- };
+ return (args && ...);
+ }
}
- namespace test_double_right_angle_brackets
+ namespace test_extended_static_assert
{
- template < typename T >
- struct check {};
+ static_assert (true);
- typedef check<void> single_type;
- typedef check<check<void>> double_type;
- typedef check<check<check<void>>> triple_type;
- typedef check<check<check<check<void>>>> quadruple_type;
+ }
+
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
}
- namespace test_decltype
+ namespace test_typename_in_template_template_parameter
{
- int
- f()
+ template<template<typename> typename X> struct D;
+
+ }
+
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
+ {
+
+ int f1()
{
- int a = 1;
- decltype(a) b = 2;
- return a + b;
+ return 42;
+ }
+
+ [[nodiscard]] int f2()
+ {
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
}
}
- namespace test_type_deduction
+ namespace test_extended_aggregate_initialization
{
- template < typename T1, typename T2 >
- struct is_same
+ struct base1
{
- static const bool value = false;
+ int b1, b2 = 42;
};
- template < typename T >
- struct is_same<T, T>
+ struct base2
{
- static const bool value = true;
+ base2() {
+ b3 = 42;
+ }
+ int b3;
};
- template < typename T1, typename T2 >
- auto
- add(T1 a1, T2 a2) -> decltype(a1 + a2)
+ struct derived : base1, base2
{
- return a1 + a2;
+ int d;
+ };
+
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
+
+ }
+
+ namespace test_general_range_based_for_loop
+ {
+
+ struct iter
+ {
+ int i;
+
+ int& operator* ()
+ {
+ return i;
+ }
+
+ const int& operator* () const
+ {
+ return i;
+ }
+
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
+
+ struct sentinel
+ {
+ int i;
+ };
+
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
}
- int
- test(const int c, volatile int v)
+ bool operator!= (const iter& i, const sentinel& s)
{
- static_assert(is_same<int, decltype(0)>::value == true, "");
- static_assert(is_same<int, decltype(c)>::value == false, "");
- static_assert(is_same<int, decltype(v)>::value == false, "");
- auto ac = c;
- auto av = v;
- auto sumi = ac + av + 'x';
- auto sumf = ac + av + 1.0;
- static_assert(is_same<int, decltype(ac)>::value == true, "");
- static_assert(is_same<int, decltype(av)>::value == true, "");
- static_assert(is_same<int, decltype(sumi)>::value == true, "");
- static_assert(is_same<int, decltype(sumf)>::value == false, "");
- static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
- return (sumf > 0.0) ? sumi : add(c, v);
+ return !(i == s);
+ }
+
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
+
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+
+ void f()
+ {
+ range r {};
+
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
}
}
- namespace test_noexcept
+ namespace test_lambda_capture_asterisk_this_by_value
{
- int f() { return 0; }
- int g() noexcept { return 0; }
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
- static_assert(noexcept(f()) == false, "");
- static_assert(noexcept(g()) == true, "");
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
}
- namespace test_constexpr
+ namespace test_constexpr_if
{
- template < typename CharT >
- unsigned long constexpr
- strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+ template <bool cond>
+ int f ()
{
- return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
}
- template < typename CharT >
- unsigned long constexpr
- strlen_c(const CharT *const s) noexcept
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
{
- return strlen_c_r(s, 0UL);
+ return 13;
}
- static_assert(strlen_c("") == 0UL, "");
- static_assert(strlen_c("1") == 1UL, "");
- static_assert(strlen_c("example") == 7UL, "");
- static_assert(strlen_c("another\0example") == 7UL, "");
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
}
- namespace test_rvalue_references
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
{
- template < int N >
- struct answer
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
{
- static constexpr int value = N;
- };
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
- answer<1> f(int&) { return answer<1>(); }
- answer<2> f(const int&) { return answer<2>(); }
- answer<3> f(int&&) { return answer<3>(); }
+ T1 m1;
+ T2 m2;
+ };
- void
- test()
+ void f()
{
- int i = 0;
- const int c = 0;
- static_assert(decltype(f(i))::value == 1, "");
- static_assert(decltype(f(c))::value == 2, "");
- static_assert(decltype(f(0))::value == 3, "");
+ [[maybe_unused]] auto p = pair{13, 42u};
}
}
+#endif // !defined(REALLY_CLANG)
- namespace test_uniform_initialization
+ namespace test_non_type_auto_template_parameters
{
- struct test
- {
- static const int zero {};
- static const int one {1};
- };
+ template <auto n>
+ struct B
+ {};
- static_assert(test::zero == 0, "");
- static_assert(test::one == 1, "");
+ B<5> b1;
+ B<'a'> b2;
}
- namespace test_lambdas
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
{
- void
- test1()
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
{
- auto lambda1 = [](){};
- auto lambda2 = lambda1;
- lambda1();
- lambda2();
+ return arr;
}
- int
- test2()
+ auto f2() -> std::pair<int, int>&
{
- auto a = [](int i, int j){ return i + j; }(1, 2);
- auto b = []() -> int { return '0'; }();
- auto c = [=](){ return a + b; }();
- auto d = [&](){ return c; }();
- auto e = [a, &b](int x) mutable {
- const auto identity = [](int y){ return y; };
- for (auto i = 0; i < a; ++i)
- a += b--;
- return x + identity(a + b);
- }(0);
- return a + b + c + d + e;
+ return pr;
}
- int
- test3()
+ struct S
{
- const auto nullary = [](){ return 0; };
- const auto unary = [](int x){ return x; };
- using nullary_t = decltype(nullary);
- using unary_t = decltype(unary);
- const auto higher1st = [](nullary_t f){ return f(); };
- const auto higher2nd = [unary](nullary_t f1){
- return [unary, f1](unary_t f2){ return f2(unary(f1())); };
- };
- return higher1st(nullary) + higher2nd(nullary)(unary);
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
}
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
}
+#endif // !defined(REALLY_CLANG)
- namespace test_variadic_templates
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
{
- template <int...>
- struct sum;
+ // TODO: test it with clang++ from git
- template <int N0, int... N1toN>
- struct sum<N0, N1toN...>
- {
- static constexpr auto value = N0 + sum<N1toN...>::value;
- };
+ struct Good {};
+ struct Bad {};
- template <>
- struct sum<>
- {
- static constexpr auto value = 0;
- };
+ void g1() noexcept;
+ void g2();
- static_assert(sum<>::value == 0, "");
- static_assert(sum<1>::value == 1, "");
- static_assert(sum<23>::value == 23, "");
- static_assert(sum<1, 2>::value == 3, "");
- static_assert(sum<5, 5, 11>::value == 21, "");
- static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+ template<typename T>
+ Bad
+ f(T*, T*);
- }
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
- // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
- // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
- // because of this.
- namespace test_template_alias_sfinae
- {
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
- struct foo {};
+ }
+#endif // !defined(REALLY_CLANG)
- template<typename T>
- using member = typename T::member_type;
+ namespace test_inline_variables
+ {
- template<typename T>
- void func(...) {}
+ template<class T> void f(T)
+ {}
- template<typename T>
- void func(member<T>*) {}
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
- void test();
+ template<> inline void f<>(int)
+ {}
- void test() { func<foo>(0); }
+ template<> int g<>(int)
+ {
+ return 5;
+ }
}
-} // namespace cxx11
+} // namespace cxx17
-#endif // __cplusplus >= 201103L
+#endif // __cplusplus <= 201402L
@@ -5980,19 +7546,19 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_c_compiler_gnu
- if test x$ax_cxx_compile_cxx11_required = xtrue; then
+ if test x$ax_cxx_compile_cxx17_required = xtrue; then
if test x$ac_success = xno; then
- as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5
+ as_fn_error $? "*** A compiler with support for C++17 language features is required." "$LINENO" 5
fi
fi
if test x$ac_success = xno; then
- HAVE_CXX11=0
- { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5
-$as_echo "$as_me: No compiler with C++11 support was found" >&6;}
+ HAVE_CXX17=0
+ { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++17 support was found" >&5
+$as_echo "$as_me: No compiler with C++17 support was found" >&6;}
else
- HAVE_CXX11=1
+ HAVE_CXX17=1
-$as_echo "#define HAVE_CXX11 1" >>confdefs.h
+$as_echo "#define HAVE_CXX17 1" >>confdefs.h
fi
diff --git a/gdbserver/configure.ac b/gdbserver/configure.ac
index 12bc0090d67..2609a11e6f6 100644
--- a/gdbserver/configure.ac
+++ b/gdbserver/configure.ac
@@ -46,9 +46,9 @@ AC_PROG_RANLIB
AC_ARG_PROGRAM
-# We require a C++11 compiler. Check if one is available, and if
+# We require a C++17 compiler. Check if one is available, and if
# necessary, set CXX_DIALECT to some -std=xxx switch.
-AX_CXX_COMPILE_STDCXX(11, , mandatory)
+AX_CXX_COMPILE_STDCXX(17, , mandatory)
AC_HEADER_STDC
diff --git a/gdbsupport/configure b/gdbsupport/configure
index 9433ac41468..cc5266ab134 100755
--- a/gdbsupport/configure
+++ b/gdbsupport/configure
@@ -656,7 +656,7 @@ LIBINTL_DEP
LIBINTL
USE_NLS
CXX_DIALECT
-HAVE_CXX11
+HAVE_CXX17
LARGEFILE_CPPFLAGS
EGREP
GREP
@@ -5905,10 +5905,10 @@ fi
-# We require a C++11 compiler. Check if one is available, and if
+# We require a C++17 compiler. Check if one is available, and if
# necessary, set CXX_DIALECT to some -std=xxx switch.
- ax_cxx_compile_alternatives="11 0x" ax_cxx_compile_cxx11_required=true
+ ax_cxx_compile_alternatives="17 1z" ax_cxx_compile_cxx17_required=true
ac_ext=cpp
ac_cpp='$CXXCPP $CPPFLAGS'
ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -5916,9 +5916,9 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
CXX_DIALECT=""
ac_success=no
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
-$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
-if ${ax_cv_cxx_compile_cxx11+:} false; then :
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features by default" >&5
+$as_echo_n "checking whether $CXX supports C++17 features by default... " >&6; }
+if ${ax_cv_cxx_compile_cxx17+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -6209,32 +6209,1399 @@ namespace cxx11
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+ namespace test_polymorphic_lambdas
+ {
+
+ int
+ test()
+ {
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
+
+ }
+
+ namespace test_binary_literals
+ {
+
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
+
+ }
+
+ namespace test_generalized_constexpr
+ {
+
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
+
+ }
+
+ namespace test_lambda_init_capture
+ {
+
+ int
+ test()
+ {
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
+ }
+
+ }
+
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
+ {
+
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static constexpr auto value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus <= 201402L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
+ {
+
+ // TODO: test it with clang++ from git
+
+ constexpr int foo = [](){return 42;}();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test::nested_namespace::definitions
+ {
+
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
+ {
+ return (args * ... * 1);
+ }
+
+ template<typename... Args>
+ bool all(Args... args)
+ {
+ return (args && ...);
+ }
+
+ }
+
+ namespace test_extended_static_assert
+ {
+
+ static_assert (true);
+
+ }
+
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
+ }
+
+ namespace test_typename_in_template_template_parameter
+ {
+
+ template<template<typename> typename X> struct D;
+
+ }
+
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
+ {
+
+ int f1()
+ {
+ return 42;
+ }
+
+ [[nodiscard]] int f2()
+ {
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
+ }
+
+ }
+
+ namespace test_extended_aggregate_initialization
+ {
+
+ struct base1
+ {
+ int b1, b2 = 42;
+ };
+
+ struct base2
+ {
+ base2() {
+ b3 = 42;
+ }
+ int b3;
+ };
+
+ struct derived : base1, base2
+ {
+ int d;
+ };
+
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
+
+ }
+
+ namespace test_general_range_based_for_loop
+ {
+
+ struct iter
+ {
+ int i;
+
+ int& operator* ()
+ {
+ return i;
+ }
+
+ const int& operator* () const
+ {
+ return i;
+ }
+
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
+
+ struct sentinel
+ {
+ int i;
+ };
+
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
+ }
+
+ bool operator!= (const iter& i, const sentinel& s)
+ {
+ return !(i == s);
+ }
+
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
+
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+
+ void f()
+ {
+ range r {};
+
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
+ }
+
+ }
+
+ namespace test_lambda_capture_asterisk_this_by_value
+ {
+
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
+
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
+
+ }
+
+ namespace test_constexpr_if
+ {
+
+ template <bool cond>
+ int f ()
+ {
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
+ }
+
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
+ {
+ return 13;
+ }
+
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
+ {
+
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
+ {
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
+
+ T1 m1;
+ T2 m2;
+ };
+
+ void f()
+ {
+ [[maybe_unused]] auto p = pair{13, 42u};
+ }
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_non_type_auto_template_parameters
+ {
+
+ template <auto n>
+ struct B
+ {};
+
+ B<5> b1;
+ B<'a'> b2;
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
+ {
+
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
+ {
+ return arr;
+ }
+
+ auto f2() -> std::pair<int, int>&
+ {
+ return pr;
+ }
+
+ struct S
+ {
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
+ }
+
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
+ {
+
+ // TODO: test it with clang++ from git
+
+ struct Good {};
+ struct Bad {};
+
+ void g1() noexcept;
+ void g2();
+
+ template<typename T>
+ Bad
+ f(T*, T*);
+
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
+
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_inline_variables
+ {
+
+ template<class T> void f(T)
+ {}
+
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
+
+ template<> inline void f<>(int)
+ {}
+
+ template<> int g<>(int)
+ {
+ return 5;
+ }
+
+ }
+
+} // namespace cxx17
+
+#endif // __cplusplus <= 201402L
+
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ ax_cv_cxx_compile_cxx17=yes
+else
+ ax_cv_cxx_compile_cxx17=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx17" >&5
+$as_echo "$ax_cv_cxx_compile_cxx17" >&6; }
+ if test x$ax_cv_cxx_compile_cxx17 = xyes; then
+ ac_success=yes
+ fi
+
+ if test x$ac_success = xno; then
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ switch="-std=gnu++${alternative}"
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
+if eval \${$cachevar+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ ac_save_CXX="$CXX"
+ CXX="$CXX $switch"
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+
+// If the compiler admits that it is not ready for C++11, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201103L
+
+#error "This is not a C++11 compiler"
+
+#else
+
+namespace cxx11
+{
+
+ namespace test_static_assert
+ {
+
+ template <typename T>
+ struct check
+ {
+ static_assert(sizeof(int) <= sizeof(T), "not big enough");
+ };
+
+ }
+
+ namespace test_final_override
+ {
+
+ struct Base
+ {
+ virtual void f() {}
+ };
+
+ struct Derived : public Base
+ {
+ virtual void f() override {}
+ };
+
+ }
+
+ namespace test_double_right_angle_brackets
+ {
+
+ template < typename T >
+ struct check {};
+
+ typedef check<void> single_type;
+ typedef check<check<void>> double_type;
+ typedef check<check<check<void>>> triple_type;
+ typedef check<check<check<check<void>>>> quadruple_type;
+
+ }
+
+ namespace test_decltype
+ {
+
+ int
+ f()
+ {
+ int a = 1;
+ decltype(a) b = 2;
+ return a + b;
+ }
+
+ }
+
+ namespace test_type_deduction
+ {
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static const bool value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static const bool value = true;
+ };
+
+ template < typename T1, typename T2 >
+ auto
+ add(T1 a1, T2 a2) -> decltype(a1 + a2)
+ {
+ return a1 + a2;
+ }
+
+ int
+ test(const int c, volatile int v)
+ {
+ static_assert(is_same<int, decltype(0)>::value == true, "");
+ static_assert(is_same<int, decltype(c)>::value == false, "");
+ static_assert(is_same<int, decltype(v)>::value == false, "");
+ auto ac = c;
+ auto av = v;
+ auto sumi = ac + av + 'x';
+ auto sumf = ac + av + 1.0;
+ static_assert(is_same<int, decltype(ac)>::value == true, "");
+ static_assert(is_same<int, decltype(av)>::value == true, "");
+ static_assert(is_same<int, decltype(sumi)>::value == true, "");
+ static_assert(is_same<int, decltype(sumf)>::value == false, "");
+ static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
+ return (sumf > 0.0) ? sumi : add(c, v);
+ }
+
+ }
+
+ namespace test_noexcept
+ {
+
+ int f() { return 0; }
+ int g() noexcept { return 0; }
+
+ static_assert(noexcept(f()) == false, "");
+ static_assert(noexcept(g()) == true, "");
+
+ }
+
+ namespace test_constexpr
+ {
+
+ template < typename CharT >
+ unsigned long constexpr
+ strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+ {
+ return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+ }
+
+ template < typename CharT >
+ unsigned long constexpr
+ strlen_c(const CharT *const s) noexcept
+ {
+ return strlen_c_r(s, 0UL);
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("1") == 1UL, "");
+ static_assert(strlen_c("example") == 7UL, "");
+ static_assert(strlen_c("another\0example") == 7UL, "");
+
+ }
+
+ namespace test_rvalue_references
+ {
+
+ template < int N >
+ struct answer
+ {
+ static constexpr int value = N;
+ };
+
+ answer<1> f(int&) { return answer<1>(); }
+ answer<2> f(const int&) { return answer<2>(); }
+ answer<3> f(int&&) { return answer<3>(); }
+
+ void
+ test()
+ {
+ int i = 0;
+ const int c = 0;
+ static_assert(decltype(f(i))::value == 1, "");
+ static_assert(decltype(f(c))::value == 2, "");
+ static_assert(decltype(f(0))::value == 3, "");
+ }
+
+ }
+
+ namespace test_uniform_initialization
+ {
+
+ struct test
+ {
+ static const int zero {};
+ static const int one {1};
+ };
+
+ static_assert(test::zero == 0, "");
+ static_assert(test::one == 1, "");
+
+ }
+
+ namespace test_lambdas
+ {
+
+ void
+ test1()
+ {
+ auto lambda1 = [](){};
+ auto lambda2 = lambda1;
+ lambda1();
+ lambda2();
+ }
+
+ int
+ test2()
+ {
+ auto a = [](int i, int j){ return i + j; }(1, 2);
+ auto b = []() -> int { return '0'; }();
+ auto c = [=](){ return a + b; }();
+ auto d = [&](){ return c; }();
+ auto e = [a, &b](int x) mutable {
+ const auto identity = [](int y){ return y; };
+ for (auto i = 0; i < a; ++i)
+ a += b--;
+ return x + identity(a + b);
+ }(0);
+ return a + b + c + d + e;
+ }
+
+ int
+ test3()
+ {
+ const auto nullary = [](){ return 0; };
+ const auto unary = [](int x){ return x; };
+ using nullary_t = decltype(nullary);
+ using unary_t = decltype(unary);
+ const auto higher1st = [](nullary_t f){ return f(); };
+ const auto higher2nd = [unary](nullary_t f1){
+ return [unary, f1](unary_t f2){ return f2(unary(f1())); };
+ };
+ return higher1st(nullary) + higher2nd(nullary)(unary);
+ }
+
+ }
+
+ namespace test_variadic_templates
+ {
+
+ template <int...>
+ struct sum;
+
+ template <int N0, int... N1toN>
+ struct sum<N0, N1toN...>
+ {
+ static constexpr auto value = N0 + sum<N1toN...>::value;
+ };
+
+ template <>
+ struct sum<>
+ {
+ static constexpr auto value = 0;
+ };
+
+ static_assert(sum<>::value == 0, "");
+ static_assert(sum<1>::value == 1, "");
+ static_assert(sum<23>::value == 23, "");
+ static_assert(sum<1, 2>::value == 3, "");
+ static_assert(sum<5, 5, 11>::value == 21, "");
+ static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+
+ }
+
+ // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+ // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
+ // because of this.
+ namespace test_template_alias_sfinae
+ {
+
+ struct foo {};
+
+ template<typename T>
+ using member = typename T::member_type;
+
+ template<typename T>
+ void func(...) {}
+
+ template<typename T>
+ void func(member<T>*) {}
+
+ void test();
+
+ void test() { func<foo>(0); }
+
+ }
+
+} // namespace cxx11
+
+#endif // __cplusplus >= 201103L
+
+
+
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+ namespace test_polymorphic_lambdas
+ {
+
+ int
+ test()
+ {
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
+
+ }
+
+ namespace test_binary_literals
+ {
+
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
+
+ }
+
+ namespace test_generalized_constexpr
+ {
+
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
+
+ }
+
+ namespace test_lambda_init_capture
+ {
+
+ int
+ test()
+ {
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
+ }
+
+ }
+
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
+ {
+
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static constexpr auto value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus <= 201402L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
+ {
+
+ // TODO: test it with clang++ from git
+
+ constexpr int foo = [](){return 42;}();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test::nested_namespace::definitions
+ {
+
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
+ {
+ return (args * ... * 1);
+ }
+
+ template<typename... Args>
+ bool all(Args... args)
+ {
+ return (args && ...);
+ }
+
+ }
+
+ namespace test_extended_static_assert
+ {
+
+ static_assert (true);
+
+ }
+
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
+ }
+
+ namespace test_typename_in_template_template_parameter
+ {
+
+ template<template<typename> typename X> struct D;
+
+ }
+
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
+ {
+
+ int f1()
+ {
+ return 42;
+ }
+
+ [[nodiscard]] int f2()
+ {
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
+ }
+
+ }
+
+ namespace test_extended_aggregate_initialization
+ {
+
+ struct base1
+ {
+ int b1, b2 = 42;
+ };
+
+ struct base2
+ {
+ base2() {
+ b3 = 42;
+ }
+ int b3;
+ };
+
+ struct derived : base1, base2
+ {
+ int d;
+ };
+
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
+
+ }
+
+ namespace test_general_range_based_for_loop
+ {
+
+ struct iter
+ {
+ int i;
+
+ int& operator* ()
+ {
+ return i;
+ }
+
+ const int& operator* () const
+ {
+ return i;
+ }
+
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
+
+ struct sentinel
+ {
+ int i;
+ };
+
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
+ }
+
+ bool operator!= (const iter& i, const sentinel& s)
+ {
+ return !(i == s);
+ }
+
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
+
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+
+ void f()
+ {
+ range r {};
+
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
+ }
+
+ }
+
+ namespace test_lambda_capture_asterisk_this_by_value
+ {
+
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
+
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
+
+ }
+
+ namespace test_constexpr_if
+ {
+
+ template <bool cond>
+ int f ()
+ {
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
+ }
+
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
+ {
+ return 13;
+ }
+
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
+ {
+
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
+ {
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
+
+ T1 m1;
+ T2 m2;
+ };
+
+ void f()
+ {
+ [[maybe_unused]] auto p = pair{13, 42u};
+ }
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_non_type_auto_template_parameters
+ {
+
+ template <auto n>
+ struct B
+ {};
+
+ B<5> b1;
+ B<'a'> b2;
+
+ }
+
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
+ {
+
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
+ {
+ return arr;
+ }
+
+ auto f2() -> std::pair<int, int>&
+ {
+ return pr;
+ }
+
+ struct S
+ {
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
+ }
+
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
+ {
+
+ // TODO: test it with clang++ from git
+
+ struct Good {};
+ struct Bad {};
+
+ void g1() noexcept;
+ void g2();
+
+ template<typename T>
+ Bad
+ f(T*, T*);
+
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
+
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+ }
+#endif // !defined(REALLY_CLANG)
+
+ namespace test_inline_variables
+ {
+
+ template<class T> void f(T)
+ {}
+
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
+
+ template<> inline void f<>(int)
+ {}
+
+ template<> int g<>(int)
+ {
+ return 5;
+ }
+
+ }
+
+} // namespace cxx17
+
+#endif // __cplusplus <= 201402L
+
+
+
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
- ax_cv_cxx_compile_cxx11=yes
+ eval $cachevar=yes
else
- ax_cv_cxx_compile_cxx11=no
+ eval $cachevar=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ CXX="$ac_save_CXX"
fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
-$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
- if test x$ax_cv_cxx_compile_cxx11 = xyes; then
- ac_success=yes
+eval ac_res=\$$cachevar
+ { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+ if eval test x\$$cachevar = xyes; then
+ CXX_DIALECT="$switch"
+ CXX="$CXX $switch"
+ if test -n "$CXXCPP" ; then
+ CXXCPP="$CXXCPP $switch"
+ fi
+ ac_success=yes
+ break
+ fi
+ done
fi
if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- switch="-std=gnu++${alternative}"
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
if eval \${$cachevar+:} false; then :
$as_echo_n "(cached) " >&6
else
ac_save_CXX="$CXX"
- CXX="$CXX $switch"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ CXX="$CXX $switch"
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
@@ -6522,326 +7889,525 @@ namespace cxx11
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
- eval $cachevar=yes
-else
- eval $cachevar=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
- CXX="$ac_save_CXX"
-fi
-eval ac_res=\$$cachevar
- { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
- if eval test x\$$cachevar = xyes; then
- CXX_DIALECT="$switch"
- CXX="$CXX $switch"
- if test -n "$CXXCPP" ; then
- CXXCPP="$CXXCPP $switch"
- fi
- ac_success=yes
- break
- fi
- done
- fi
- if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
-if eval \${$cachevar+:} false; then :
- $as_echo_n "(cached) " >&6
-else
- ac_save_CXX="$CXX"
- CXX="$CXX $switch"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h. */
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+ namespace test_polymorphic_lambdas
+ {
+
+ int
+ test()
+ {
+ const auto lambda = [](auto&&... args){
+ const auto istiny = [](auto x){
+ return (sizeof(x) == 1UL) ? 1 : 0;
+ };
+ const int aretiny[] = { istiny(args)... };
+ return aretiny[0];
+ };
+ return lambda(1, 1L, 1.0f, '1');
+ }
+
+ }
+
+ namespace test_binary_literals
+ {
+
+ constexpr auto ivii = 0b0000000000101010;
+ static_assert(ivii == 42, "wrong value");
+
+ }
+
+ namespace test_generalized_constexpr
+ {
+
+ template < typename CharT >
+ constexpr unsigned long
+ strlen_c(const CharT *const s) noexcept
+ {
+ auto length = 0UL;
+ for (auto p = s; *p; ++p)
+ ++length;
+ return length;
+ }
+
+ static_assert(strlen_c("") == 0UL, "");
+ static_assert(strlen_c("x") == 1UL, "");
+ static_assert(strlen_c("test") == 4UL, "");
+ static_assert(strlen_c("another\0test") == 7UL, "");
+
+ }
+
+ namespace test_lambda_init_capture
+ {
+
+ int
+ test()
+ {
+ auto x = 0;
+ const auto lambda1 = [a = x](int b){ return a + b; };
+ const auto lambda2 = [a = lambda1(x)](){ return a; };
+ return lambda2();
+ }
+
+ }
+
+ namespace test_digit_separators
+ {
+
+ constexpr auto ten_million = 100'000'000;
+ static_assert(ten_million == 100000000, "");
+
+ }
+
+ namespace test_return_type_deduction
+ {
+
+ auto f(int& x) { return x; }
+ decltype(auto) g(int& x) { return x; }
+
+ template < typename T1, typename T2 >
+ struct is_same
+ {
+ static constexpr auto value = false;
+ };
+
+ template < typename T >
+ struct is_same<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+} // namespace cxx14
-// If the compiler admits that it is not ready for C++11, why torture it?
+#endif // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
// Hopefully, this will speed up the test.
#ifndef __cplusplus
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+#elif __cplusplus <= 201402L
-#error "This is not a C++11 compiler"
+#error "This is not a C++17 compiler"
#else
-namespace cxx11
+#if defined(__clang__)
+ #define REALLY_CLANG
+#else
+ #if defined(__GNUC__)
+ #define REALLY_GCC
+ #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
{
- namespace test_static_assert
+#if !defined(REALLY_CLANG)
+ namespace test_constexpr_lambdas
{
- template <typename T>
- struct check
- {
- static_assert(sizeof(int) <= sizeof(T), "not big enough");
- };
+ // TODO: test it with clang++ from git
+
+ constexpr int foo = [](){return 42;}();
}
+#endif // !defined(REALLY_CLANG)
- namespace test_final_override
+ namespace test::nested_namespace::definitions
{
- struct Base
+ }
+
+ namespace test_fold_expression
+ {
+
+ template<typename... Args>
+ int multiply(Args... args)
{
- virtual void f() {}
- };
+ return (args * ... * 1);
+ }
- struct Derived : public Base
+ template<typename... Args>
+ bool all(Args... args)
{
- virtual void f() override {}
- };
+ return (args && ...);
+ }
}
- namespace test_double_right_angle_brackets
+ namespace test_extended_static_assert
{
- template < typename T >
- struct check {};
+ static_assert (true);
- typedef check<void> single_type;
- typedef check<check<void>> double_type;
- typedef check<check<check<void>>> triple_type;
- typedef check<check<check<check<void>>>> quadruple_type;
+ }
+
+ namespace test_auto_brace_init_list
+ {
+
+ auto foo = {5};
+ auto bar {5};
+ static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+ static_assert(std::is_same<int, decltype(bar)>::value);
}
- namespace test_decltype
+ namespace test_typename_in_template_template_parameter
{
- int
- f()
+ template<template<typename> typename X> struct D;
+
+ }
+
+ namespace test_fallthrough_nodiscard_maybe_unused_attributes
+ {
+
+ int f1()
{
- int a = 1;
- decltype(a) b = 2;
- return a + b;
+ return 42;
+ }
+
+ [[nodiscard]] int f2()
+ {
+ [[maybe_unused]] auto unused = f1();
+
+ switch (f1())
+ {
+ case 17:
+ f1();
+ [[fallthrough]];
+ case 42:
+ f1();
+ }
+ return f1();
}
}
- namespace test_type_deduction
+ namespace test_extended_aggregate_initialization
{
- template < typename T1, typename T2 >
- struct is_same
+ struct base1
{
- static const bool value = false;
+ int b1, b2 = 42;
};
- template < typename T >
- struct is_same<T, T>
+ struct base2
{
- static const bool value = true;
+ base2() {
+ b3 = 42;
+ }
+ int b3;
};
- template < typename T1, typename T2 >
- auto
- add(T1 a1, T2 a2) -> decltype(a1 + a2)
+ struct derived : base1, base2
{
- return a1 + a2;
+ int d;
+ };
+
+ derived d1 {{1, 2}, {}, 4}; // full initialization
+ derived d2 {{}, {}, 4}; // value-initialized bases
+
+ }
+
+ namespace test_general_range_based_for_loop
+ {
+
+ struct iter
+ {
+ int i;
+
+ int& operator* ()
+ {
+ return i;
+ }
+
+ const int& operator* () const
+ {
+ return i;
+ }
+
+ iter& operator++()
+ {
+ ++i;
+ return *this;
+ }
+ };
+
+ struct sentinel
+ {
+ int i;
+ };
+
+ bool operator== (const iter& i, const sentinel& s)
+ {
+ return i.i == s.i;
}
- int
- test(const int c, volatile int v)
+ bool operator!= (const iter& i, const sentinel& s)
{
- static_assert(is_same<int, decltype(0)>::value == true, "");
- static_assert(is_same<int, decltype(c)>::value == false, "");
- static_assert(is_same<int, decltype(v)>::value == false, "");
- auto ac = c;
- auto av = v;
- auto sumi = ac + av + 'x';
- auto sumf = ac + av + 1.0;
- static_assert(is_same<int, decltype(ac)>::value == true, "");
- static_assert(is_same<int, decltype(av)>::value == true, "");
- static_assert(is_same<int, decltype(sumi)>::value == true, "");
- static_assert(is_same<int, decltype(sumf)>::value == false, "");
- static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
- return (sumf > 0.0) ? sumi : add(c, v);
+ return !(i == s);
+ }
+
+ struct range
+ {
+ iter begin() const
+ {
+ return {0};
+ }
+
+ sentinel end() const
+ {
+ return {5};
+ }
+ };
+
+ void f()
+ {
+ range r {};
+
+ for (auto i : r)
+ {
+ [[maybe_unused]] auto v = i;
+ }
}
}
- namespace test_noexcept
+ namespace test_lambda_capture_asterisk_this_by_value
{
- int f() { return 0; }
- int g() noexcept { return 0; }
+ struct t
+ {
+ int i;
+ int foo()
+ {
+ return [*this]()
+ {
+ return i;
+ }();
+ }
+ };
- static_assert(noexcept(f()) == false, "");
- static_assert(noexcept(g()) == true, "");
+ }
+
+ namespace test_enum_class_construction
+ {
+
+ enum class byte : unsigned char
+ {};
+
+ byte foo {42};
}
- namespace test_constexpr
+ namespace test_constexpr_if
{
- template < typename CharT >
- unsigned long constexpr
- strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+ template <bool cond>
+ int f ()
{
- return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+ if constexpr(cond)
+ {
+ return 13;
+ }
+ else
+ {
+ return 42;
+ }
}
- template < typename CharT >
- unsigned long constexpr
- strlen_c(const CharT *const s) noexcept
+ }
+
+ namespace test_selection_statement_with_initializer
+ {
+
+ int f()
{
- return strlen_c_r(s, 0UL);
+ return 13;
}
- static_assert(strlen_c("") == 0UL, "");
- static_assert(strlen_c("1") == 1UL, "");
- static_assert(strlen_c("example") == 7UL, "");
- static_assert(strlen_c("another\0example") == 7UL, "");
+ int f2()
+ {
+ if (auto i = f(); i > 0)
+ {
+ return 3;
+ }
+
+ switch (auto i = f(); i + 4)
+ {
+ case 17:
+ return 2;
+
+ default:
+ return 1;
+ }
+ }
}
- namespace test_rvalue_references
+#if !defined(REALLY_CLANG)
+ namespace test_template_argument_deduction_for_class_templates
{
- template < int N >
- struct answer
+ // TODO: test it with clang++ from git
+
+ template <typename T1, typename T2>
+ struct pair
{
- static constexpr int value = N;
- };
+ pair (T1 p1, T2 p2)
+ : m1 {p1},
+ m2 {p2}
+ {}
- answer<1> f(int&) { return answer<1>(); }
- answer<2> f(const int&) { return answer<2>(); }
- answer<3> f(int&&) { return answer<3>(); }
+ T1 m1;
+ T2 m2;
+ };
- void
- test()
+ void f()
{
- int i = 0;
- const int c = 0;
- static_assert(decltype(f(i))::value == 1, "");
- static_assert(decltype(f(c))::value == 2, "");
- static_assert(decltype(f(0))::value == 3, "");
+ [[maybe_unused]] auto p = pair{13, 42u};
}
}
+#endif // !defined(REALLY_CLANG)
- namespace test_uniform_initialization
+ namespace test_non_type_auto_template_parameters
{
- struct test
- {
- static const int zero {};
- static const int one {1};
- };
+ template <auto n>
+ struct B
+ {};
- static_assert(test::zero == 0, "");
- static_assert(test::one == 1, "");
+ B<5> b1;
+ B<'a'> b2;
}
- namespace test_lambdas
+#if !defined(REALLY_CLANG)
+ namespace test_structured_bindings
{
- void
- test1()
+ // TODO: test it with clang++ from git
+
+ int arr[2] = { 1, 2 };
+ std::pair<int, int> pr = { 1, 2 };
+
+ auto f1() -> int(&)[2]
{
- auto lambda1 = [](){};
- auto lambda2 = lambda1;
- lambda1();
- lambda2();
+ return arr;
}
- int
- test2()
+ auto f2() -> std::pair<int, int>&
{
- auto a = [](int i, int j){ return i + j; }(1, 2);
- auto b = []() -> int { return '0'; }();
- auto c = [=](){ return a + b; }();
- auto d = [&](){ return c; }();
- auto e = [a, &b](int x) mutable {
- const auto identity = [](int y){ return y; };
- for (auto i = 0; i < a; ++i)
- a += b--;
- return x + identity(a + b);
- }(0);
- return a + b + c + d + e;
+ return pr;
}
- int
- test3()
+ struct S
{
- const auto nullary = [](){ return 0; };
- const auto unary = [](int x){ return x; };
- using nullary_t = decltype(nullary);
- using unary_t = decltype(unary);
- const auto higher1st = [](nullary_t f){ return f(); };
- const auto higher2nd = [unary](nullary_t f1){
- return [unary, f1](unary_t f2){ return f2(unary(f1())); };
- };
- return higher1st(nullary) + higher2nd(nullary)(unary);
+ int x1 : 2;
+ volatile double y1;
+ };
+
+ S f3()
+ {
+ return {};
}
+ auto [ x1, y1 ] = f1();
+ auto& [ xr1, yr1 ] = f1();
+ auto [ x2, y2 ] = f2();
+ auto& [ xr2, yr2 ] = f2();
+ const auto [ x3, y3 ] = f3();
+
}
+#endif // !defined(REALLY_CLANG)
- namespace test_variadic_templates
+#if !defined(REALLY_CLANG)
+ namespace test_exception_spec_type_system
{
- template <int...>
- struct sum;
+ // TODO: test it with clang++ from git
- template <int N0, int... N1toN>
- struct sum<N0, N1toN...>
- {
- static constexpr auto value = N0 + sum<N1toN...>::value;
- };
+ struct Good {};
+ struct Bad {};
- template <>
- struct sum<>
- {
- static constexpr auto value = 0;
- };
+ void g1() noexcept;
+ void g2();
- static_assert(sum<>::value == 0, "");
- static_assert(sum<1>::value == 1, "");
- static_assert(sum<23>::value == 23, "");
- static_assert(sum<1, 2>::value == 3, "");
- static_assert(sum<5, 5, 11>::value == 21, "");
- static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+ template<typename T>
+ Bad
+ f(T*, T*);
- }
+ template<typename T1, typename T2>
+ Good
+ f(T1*, T2*);
- // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
- // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
- // because of this.
- namespace test_template_alias_sfinae
- {
+ static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
- struct foo {};
+ }
+#endif // !defined(REALLY_CLANG)
- template<typename T>
- using member = typename T::member_type;
+ namespace test_inline_variables
+ {
- template<typename T>
- void func(...) {}
+ template<class T> void f(T)
+ {}
- template<typename T>
- void func(member<T>*) {}
+ template<class T> inline T g(T)
+ {
+ return T{};
+ }
- void test();
+ template<> inline void f<>(int)
+ {}
- void test() { func<foo>(0); }
+ template<> int g<>(int)
+ {
+ return 5;
+ }
}
-} // namespace cxx11
+} // namespace cxx17
-#endif // __cplusplus >= 201103L
+#endif // __cplusplus <= 201402L
@@ -6878,19 +8444,19 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_c_compiler_gnu
- if test x$ax_cxx_compile_cxx11_required = xtrue; then
+ if test x$ax_cxx_compile_cxx17_required = xtrue; then
if test x$ac_success = xno; then
- as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5
+ as_fn_error $? "*** A compiler with support for C++17 language features is required." "$LINENO" 5
fi
fi
if test x$ac_success = xno; then
- HAVE_CXX11=0
- { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5
-$as_echo "$as_me: No compiler with C++11 support was found" >&6;}
+ HAVE_CXX17=0
+ { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++17 support was found" >&5
+$as_echo "$as_me: No compiler with C++17 support was found" >&6;}
else
- HAVE_CXX11=1
+ HAVE_CXX17=1
-$as_echo "#define HAVE_CXX11 1" >>confdefs.h
+$as_echo "#define HAVE_CXX17 1" >>confdefs.h
fi
diff --git a/gdbsupport/configure.ac b/gdbsupport/configure.ac
index 2cb382bd4ec..a0986fab9cd 100644
--- a/gdbsupport/configure.ac
+++ b/gdbsupport/configure.ac
@@ -41,9 +41,9 @@ AC_PROG_RANLIB
AC_USE_SYSTEM_EXTENSIONS
ACX_LARGEFILE
-# We require a C++11 compiler. Check if one is available, and if
+# We require a C++17 compiler. Check if one is available, and if
# necessary, set CXX_DIALECT to some -std=xxx switch.
-AX_CXX_COMPILE_STDCXX(11, , mandatory)
+AX_CXX_COMPILE_STDCXX(17, , mandatory)
dnl Set up for gettext.
ZW_GNU_GETTEXT_SISTER_DIR
base-commit: 29d1b2baed8be0018ed8653745fdf8de966ea2a2
--
2.35.3
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH RFC] Require c++17 compiler
2023-10-05 6:54 [RFC] [gdb/build] Require c++17 compiler Tom de Vries
@ 2023-10-05 10:33 ` Lancelot SIX
2023-10-05 12:26 ` Andrew Burgess
2023-10-12 17:30 ` Pedro Alves
2023-10-05 15:31 ` [RFC] [gdb/build] " Tom Tromey
` (2 subsequent siblings)
3 siblings, 2 replies; 14+ messages in thread
From: Lancelot SIX @ 2023-10-05 10:33 UTC (permalink / raw)
To: Tom de Vries; +Cc: gdb-patches
[-- Attachment #1: Type: text/plain, Size: 5352 bytes --]
Hi Tom,
Thanks for putting this together! As you know, I am in favor of such
change (for GDB-15 probably, GDB-14 branching is probably too close)!
I do have a really similar patch available on a local branch. One
difference though is that my branch uses a preparatory patch to upgrade
gdb/ax_cxx_compile_stdcxx.m4 to follow upstream changes to this file.
This upgrade gives some improvements in the C++17 compiler detection.
We keep this in the GDB tree because it has some local changes to set
CXX_DIALECT. This preparatory patch should be included in this reply.
On Thu, Oct 05, 2023 at 08:54:49AM +0200, Tom de Vries wrote:
> Since gdb 8.0, we've required a c++11 compiler.
>
> That allowed gdb to be compiled with gcc releases as far back as gcc 4.8,
> using an explicit -std=c++11 to override the default.
>
> [ Gcc has the following defaults:
> - before gcc 6: c++98, and
> - for gcc 6-10: c++14, and
> - since gcc 11: c++17. ]
>
> There are two arguments in favor of moving to requiring a newer c++ standard:
> - benefits can be had from using newer c++ features. We're already using some
> of those features using gdb-specific implementations.
> - when developing gdb on modern platforms with system compiler gcc >= 6,
> people can accidentally use c++14/c++17 features in a patch, only to find out
> post-commit that it breaks the build on a system with a compiler that only
> supports c++11, which is inconvenient and takes time to fix.
> [ This could be partially mitigated by if possible also forcing -std=c++11
> for such compilers. ]
Thanks for pointing this out, this was one trigger for me to start
looking into this!
>
> The need to keep requiring c++11 comes from porting new gdb releases to older
> systems with older system compilers.
>
> A review of some relevant distros has shown that in case that requiring c++17
> results in no longer being able to use the system compiler, an alternative,
> newer compiler that does support c++17 is readily available.
>
> With nothing holding back the change, require a c++17 compiler to build gdb.
Just for the record, it might be worth mentioning here the general
policy of the project regarding bumping the C++ required version:
https://sourceware.org/gdb/wiki/Internals%20GDB-C-Coding-Standards#When_is_GDB_going_to_start_requiring_C.2B-.2B-NN_.3F
>
> The gcc documentation ( https://gcc.gnu.org/projects/cxx-status.html ) states
> that "Some C++17 features are available since GCC 5, but support was
> experimental and the ABI of C++17 features was not stable until GCC 9".
>
> Consequently, the NEWS item mentions gcc 9 as an example compiler to use.
>
> My understanding of using gcc 5-8 is that it works as long as gdb doesn't use
> not yet available language features. Of course the set of used language
> features may change in time, so what compiler still works may change.
>
> Problems can arise when shared libs starts to have C++17 based APIs (or
> somehow expose instantiations of such classes). If compiled with a compiler
> in which c++17 support was still experimental, it may be incompatible when
> linking with:
> - code compiled with a compiler with non-experimental c++17 support, or
> - code compiled with a different compiler with experimental c++17 support.
>
> Looking at the current implementation of our only shared lib:
> libinproctrace.so, I couldn't spot any c++ usage in the API, so I'm assuming
> this problem is not likely to happen.
>
> Requiring c++17 means we can drop some code:
> ...
> $ find gdb* -type f \
> | egrep -v "/configure|\.m4" \
> | xargs grep "# *if.*__cplusplus.*2014"
> gdb/cp-support.c:#if __cplusplus >= 201402L
> gdb/dwarf2/cooked-index.c:#if __cplusplus >= 201402L
> gdbsupport/gdb_optional.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
> gdbsupport/gdb_optional.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
> gdbsupport/gdb_unique_ptr.h:#if __cplusplus >= 201402L
> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
> $ find gdb* -type f \
> | egrep -v "/configure|\.m4" \
> | xargs grep "# *if.*__cplusplus.*2017"
> gdb/unittests/string_view-selftests.c:#if __cplusplus < 201703L
> gdb/disasm.h:#if __cplusplus >= 201703L
> gdbsupport/invoke-result.h:#if __cplusplus >= 201703L
> gdbsupport/gdb_string_view.h:#if __cplusplus >= 201703L
> ...
> but that's not yet included in this patch.
If this patch is accepted, one change I'd like is to do is drop
gdb::make_unique, because 1) the current fallback we have for C++11
compilers is not entirely compatible with std::make_unique (the T[] case
is not supported properly I think), and 2) it is not widely used yet, so
"it's not too late" :D
Best,
Lancelot.
>
> Tested on x86_64-linux.
> ---
> gdb/NEWS | 3 +
> gdb/configure | 2030 ++++++++++++++++++++++++++++++++++-----
> gdb/configure.ac | 4 +-
> gdbserver/configure | 2018 +++++++++++++++++++++++++++++++++-----
> gdbserver/configure.ac | 4 +-
> gdbsupport/configure | 2018 +++++++++++++++++++++++++++++++++-----
> gdbsupport/configure.ac | 4 +-
> 7 files changed, 5391 insertions(+), 690 deletions(-)
[-- Attachment #2: 0001-gdb-ax_cxx_compile_stdcxx.m4-upgrade.patch --]
[-- Type: text/x-diff, Size: 22819 bytes --]
From addad71b1b2cc74b05c79a8cd87bb824ef39429e Mon Sep 17 00:00:00 2001
From: Lancelot Six <lancelot.six@amd.com>
Date: Tue, 12 Sep 2023 13:13:23 +0000
Subject: [PATCH] gdb/ax_cxx_compile_stdcxx.m4: upgrade
This patch upgrades gdb/ax_cxx_compile_stdcxx.m4 to follow changes
available in [1] and regenerates the configure script.
[1] https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
Change-Id: I5b16adc65c9e48a13ad65202d58ab7a9d487214e
---
gdb/ax_cxx_compile_stdcxx.m4 | 126 +++++++++++++++++++++++------------
gdb/configure | 44 +++++++++---
gdbserver/configure | 44 +++++++++---
gdbsupport/configure | 44 +++++++++---
4 files changed, 184 insertions(+), 74 deletions(-)
diff --git a/gdb/ax_cxx_compile_stdcxx.m4 b/gdb/ax_cxx_compile_stdcxx.m4
index 68ff8a553f0..b0432599489 100644
--- a/gdb/ax_cxx_compile_stdcxx.m4
+++ b/gdb/ax_cxx_compile_stdcxx.m4
@@ -19,13 +19,13 @@
#
# Check for baseline language coverage in the compiler for the specified
# version of the C++ standard. If necessary, add switches to CXX and
-# CXXCPP to enable support. VERSION may be '11' (for the C++11 standard)
-# or '14' (for the C++14 standard).
+# CXXCPP to enable support. VERSION may be '11', '14', '17', or '20' for
+# the respective C++ standard version.
#
# The second argument, if specified, indicates whether you insist on an
# extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
# -std=c++11). If neither is specified, you get whatever works, with
-# preference for an extended mode.
+# preference for no added switch, and then for an extended mode.
#
# The third argument, if specified 'mandatory' or if left unspecified,
# indicates that baseline support for the specified C++ standard is
@@ -42,14 +42,17 @@
# Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
# Copyright (c) 2015 Paul Norman <penorman@mac.com>
# Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
-# Copyright (c) 2016 Krzesimir Nowak <qdlacz@gmail.com>
+# Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com>
+# Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com>
+# Copyright (c) 2020 Jason Merrill <jason@redhat.com>
+# Copyright (c) 2021 Jörn Heusipp <osmanx@problemloesungsmaschine.de>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
-#serial 8
+#serial 18
dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
dnl (serial version number 13).
@@ -58,6 +61,7 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
[$1], [14], [ax_cxx_compile_alternatives="14 1y"],
[$1], [17], [ax_cxx_compile_alternatives="17 1z"],
+ [$1], [20], [ax_cxx_compile_alternatives="20"],
[m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
m4_if([$2], [], [],
[$2], [ext], [],
@@ -70,14 +74,16 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
AC_LANG_PUSH([C++])dnl
CXX_DIALECT=""
ac_success=no
- AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
- ax_cv_cxx_compile_cxx$1,
- [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
- [ax_cv_cxx_compile_cxx$1=yes],
- [ax_cv_cxx_compile_cxx$1=no])])
- if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
- ac_success=yes
- fi
+
+ m4_if([$2], [], [dnl
+ AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
+ ax_cv_cxx_compile_cxx$1,
+ [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+ [ax_cv_cxx_compile_cxx$1=yes],
+ [ax_cv_cxx_compile_cxx$1=no])])
+ if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
+ ac_success=yes
+ fi])
m4_if([$2], [noext], [], [dnl
if test x$ac_success = xno; then
@@ -109,9 +115,18 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
dnl HP's aCC needs +std=c++11 according to:
dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
dnl Cray's crayCC needs "-h std=c++11"
+ dnl MSVC needs -std:c++NN for C++17 and later (default is C++14)
for alternative in ${ax_cxx_compile_alternatives}; do
- for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
- cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+ for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+ if test x"$switch" = xMSVC; then
+ dnl AS_TR_SH maps both `:` and `=` to `_` so -std:c++17 would collide
+ dnl with -std=c++17. We suffix the cache variable name with _MSVC to
+ dnl avoid this.
+ switch=-std:c++${alternative}
+ cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_${switch}_MSVC])
+ else
+ cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+ fi
AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
$cachevar,
[ac_save_CXX="$CXX"
@@ -160,7 +175,6 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
)
-
dnl Test body for checking C++14 support
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
@@ -168,12 +182,24 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
_AX_CXX_COMPILE_STDCXX_testbody_new_in_14
)
+dnl Test body for checking C++17 support
+
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
_AX_CXX_COMPILE_STDCXX_testbody_new_in_14
_AX_CXX_COMPILE_STDCXX_testbody_new_in_17
)
+dnl Test body for checking C++20 support
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_20],
+ _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
+ _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
+ _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
+ _AX_CXX_COMPILE_STDCXX_testbody_new_in_20
+)
+
+
dnl Tests for new features in C++11
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
@@ -185,7 +211,11 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -210,11 +240,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
@@ -474,7 +506,7 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
#error "This is not a C++ compiler"
-#elif __cplusplus < 201402L
+#elif __cplusplus < 201402L && !defined _MSC_VER
#error "This is not a C++14 compiler"
@@ -598,20 +630,12 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
#error "This is not a C++ compiler"
-#elif __cplusplus <= 201402L
+#elif __cplusplus < 201703L && !defined _MSC_VER
#error "This is not a C++17 compiler"
#else
-#if defined(__clang__)
- #define REALLY_CLANG
-#else
- #if defined(__GNUC__)
- #define REALLY_GCC
- #endif
-#endif
-
#include <initializer_list>
#include <utility>
#include <type_traits>
@@ -619,16 +643,12 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
namespace cxx17
{
-#if !defined(REALLY_CLANG)
namespace test_constexpr_lambdas
{
- // TODO: test it with clang++ from git
-
constexpr int foo = [](){return 42;}();
}
-#endif // !defined(REALLY_CLANG)
namespace test::nested_namespace::definitions
{
@@ -863,12 +883,9 @@ namespace cxx17
}
-#if !defined(REALLY_CLANG)
namespace test_template_argument_deduction_for_class_templates
{
- // TODO: test it with clang++ from git
-
template <typename T1, typename T2>
struct pair
{
@@ -887,7 +904,6 @@ namespace cxx17
}
}
-#endif // !defined(REALLY_CLANG)
namespace test_non_type_auto_template_parameters
{
@@ -901,12 +917,9 @@ namespace cxx17
}
-#if !defined(REALLY_CLANG)
namespace test_structured_bindings
{
- // TODO: test it with clang++ from git
-
int arr[2] = { 1, 2 };
std::pair<int, int> pr = { 1, 2 };
@@ -938,14 +951,10 @@ namespace cxx17
const auto [ x3, y3 ] = f3();
}
-#endif // !defined(REALLY_CLANG)
-#if !defined(REALLY_CLANG)
namespace test_exception_spec_type_system
{
- // TODO: test it with clang++ from git
-
struct Good {};
struct Bad {};
@@ -963,7 +972,6 @@ namespace cxx17
static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
}
-#endif // !defined(REALLY_CLANG)
namespace test_inline_variables
{
@@ -988,6 +996,36 @@ namespace cxx17
} // namespace cxx17
-#endif // __cplusplus <= 201402L
+#endif // __cplusplus < 201703L && !defined _MSC_VER
+
+]])
+
+
+dnl Tests for new features in C++20
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_20], [[
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 202002L && !defined _MSC_VER
+
+#error "This is not a C++20 compiler"
+
+#else
+
+#include <version>
+
+namespace cxx20
+{
+
+// As C++20 supports feature test macros in the standard, there is no
+// immediate need to actually test for feature availability on the
+// Autoconf side.
+
+} // namespace cxx20
+
+#endif // __cplusplus < 202002L && !defined _MSC_VER
]])
diff --git a/gdb/configure b/gdb/configure
index 2d07e0cb596..df17060bf39 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -16497,7 +16497,8 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
CXX_DIALECT=""
ac_success=no
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
+
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
if ${ax_cv_cxx_compile_cxx11+:} false; then :
$as_echo_n "(cached) " >&6
@@ -16513,7 +16514,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -16538,11 +16543,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
@@ -16800,9 +16807,9 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
- if test x$ax_cv_cxx_compile_cxx11 = xyes; then
- ac_success=yes
- fi
+ if test x$ax_cv_cxx_compile_cxx11 = xyes; then
+ ac_success=yes
+ fi
if test x$ac_success = xno; then
for alternative in ${ax_cxx_compile_alternatives}; do
@@ -16826,7 +16833,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -16851,11 +16862,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
@@ -17128,9 +17141,14 @@ $as_echo "$ac_res" >&6; }
fi
if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+ if test x"$switch" = xMSVC; then
+ switch=-std:c++${alternative}
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_${switch}_MSVC" | $as_tr_sh`
+ else
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
+ fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
if eval \${$cachevar+:} false; then :
@@ -17149,7 +17167,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -17174,11 +17196,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
diff --git a/gdbserver/configure b/gdbserver/configure
index e807c60c08a..dc2f4146713 100755
--- a/gdbserver/configure
+++ b/gdbserver/configure
@@ -5018,7 +5018,8 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
CXX_DIALECT=""
ac_success=no
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
+
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
if ${ax_cv_cxx_compile_cxx11+:} false; then :
$as_echo_n "(cached) " >&6
@@ -5034,7 +5035,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -5059,11 +5064,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
@@ -5321,9 +5328,9 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
- if test x$ax_cv_cxx_compile_cxx11 = xyes; then
- ac_success=yes
- fi
+ if test x$ax_cv_cxx_compile_cxx11 = xyes; then
+ ac_success=yes
+ fi
if test x$ac_success = xno; then
for alternative in ${ax_cxx_compile_alternatives}; do
@@ -5347,7 +5354,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -5372,11 +5383,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
@@ -5649,9 +5662,14 @@ $as_echo "$ac_res" >&6; }
fi
if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+ if test x"$switch" = xMSVC; then
+ switch=-std:c++${alternative}
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_${switch}_MSVC" | $as_tr_sh`
+ else
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
+ fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
if eval \${$cachevar+:} false; then :
@@ -5670,7 +5688,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -5695,11 +5717,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
diff --git a/gdbsupport/configure b/gdbsupport/configure
index 9433ac41468..08531fcbed5 100755
--- a/gdbsupport/configure
+++ b/gdbsupport/configure
@@ -5916,7 +5916,8 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
CXX_DIALECT=""
ac_success=no
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
+
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
if ${ax_cv_cxx_compile_cxx11+:} false; then :
$as_echo_n "(cached) " >&6
@@ -5932,7 +5933,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -5957,11 +5962,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
@@ -6219,9 +6226,9 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
- if test x$ax_cv_cxx_compile_cxx11 = xyes; then
- ac_success=yes
- fi
+ if test x$ax_cv_cxx_compile_cxx11 = xyes; then
+ ac_success=yes
+ fi
if test x$ac_success = xno; then
for alternative in ${ax_cxx_compile_alternatives}; do
@@ -6245,7 +6252,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -6270,11 +6281,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
@@ -6547,9 +6560,14 @@ $as_echo "$ac_res" >&6; }
fi
if test x$ac_success = xno; then
- for alternative in ${ax_cxx_compile_alternatives}; do
- for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
- cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+ if test x"$switch" = xMSVC; then
+ switch=-std:c++${alternative}
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_${switch}_MSVC" | $as_tr_sh`
+ else
+ cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
+ fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
if eval \${$cachevar+:} false; then :
@@ -6568,7 +6586,11 @@ else
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
@@ -6593,11 +6615,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
--
2.34.1
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH RFC] Require c++17 compiler
2023-10-05 10:33 ` [PATCH RFC] " Lancelot SIX
@ 2023-10-05 12:26 ` Andrew Burgess
2023-10-05 14:26 ` Lancelot SIX
2023-10-12 17:30 ` Pedro Alves
1 sibling, 1 reply; 14+ messages in thread
From: Andrew Burgess @ 2023-10-05 12:26 UTC (permalink / raw)
To: Lancelot SIX, Tom de Vries; +Cc: gdb-patches
Lancelot SIX via Gdb-patches <gdb-patches@sourceware.org> writes:
> Hi Tom,
>
> Thanks for putting this together! As you know, I am in favor of such
> change (for GDB-15 probably, GDB-14 branching is probably too close)!
>
> I do have a really similar patch available on a local branch. One
> difference though is that my branch uses a preparatory patch to upgrade
> gdb/ax_cxx_compile_stdcxx.m4 to follow upstream changes to this file.
> This upgrade gives some improvements in the C++17 compiler detection.
> We keep this in the GDB tree because it has some local changes to set
> CXX_DIALECT. This preparatory patch should be included in this reply.
>
> On Thu, Oct 05, 2023 at 08:54:49AM +0200, Tom de Vries wrote:
>> Since gdb 8.0, we've required a c++11 compiler.
>>
>> That allowed gdb to be compiled with gcc releases as far back as gcc 4.8,
>> using an explicit -std=c++11 to override the default.
>>
>> [ Gcc has the following defaults:
>> - before gcc 6: c++98, and
>> - for gcc 6-10: c++14, and
>> - since gcc 11: c++17. ]
>>
>> There are two arguments in favor of moving to requiring a newer c++ standard:
>> - benefits can be had from using newer c++ features. We're already using some
>> of those features using gdb-specific implementations.
>> - when developing gdb on modern platforms with system compiler gcc >= 6,
>> people can accidentally use c++14/c++17 features in a patch, only to find out
>> post-commit that it breaks the build on a system with a compiler that only
>> supports c++11, which is inconvenient and takes time to fix.
>> [ This could be partially mitigated by if possible also forcing -std=c++11
>> for such compilers. ]
>
> Thanks for pointing this out, this was one trigger for me to start
> looking into this!
>
>>
>> The need to keep requiring c++11 comes from porting new gdb releases to older
>> systems with older system compilers.
>>
>> A review of some relevant distros has shown that in case that requiring c++17
>> results in no longer being able to use the system compiler, an alternative,
>> newer compiler that does support c++17 is readily available.
>>
>> With nothing holding back the change, require a c++17 compiler to build gdb.
>
> Just for the record, it might be worth mentioning here the general
> policy of the project regarding bumping the C++ required version:
> https://sourceware.org/gdb/wiki/Internals%20GDB-C-Coding-Standards#When_is_GDB_going_to_start_requiring_C.2B-.2B-NN_.3F
>
>>
>> The gcc documentation ( https://gcc.gnu.org/projects/cxx-status.html ) states
>> that "Some C++17 features are available since GCC 5, but support was
>> experimental and the ABI of C++17 features was not stable until GCC 9".
>>
>> Consequently, the NEWS item mentions gcc 9 as an example compiler to use.
>>
>> My understanding of using gcc 5-8 is that it works as long as gdb doesn't use
>> not yet available language features. Of course the set of used language
>> features may change in time, so what compiler still works may change.
>>
>> Problems can arise when shared libs starts to have C++17 based APIs (or
>> somehow expose instantiations of such classes). If compiled with a compiler
>> in which c++17 support was still experimental, it may be incompatible when
>> linking with:
>> - code compiled with a compiler with non-experimental c++17 support, or
>> - code compiled with a different compiler with experimental c++17 support.
>>
>> Looking at the current implementation of our only shared lib:
>> libinproctrace.so, I couldn't spot any c++ usage in the API, so I'm assuming
>> this problem is not likely to happen.
>>
>> Requiring c++17 means we can drop some code:
>> ...
>> $ find gdb* -type f \
>> | egrep -v "/configure|\.m4" \
>> | xargs grep "# *if.*__cplusplus.*2014"
>> gdb/cp-support.c:#if __cplusplus >= 201402L
>> gdb/dwarf2/cooked-index.c:#if __cplusplus >= 201402L
>> gdbsupport/gdb_optional.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>> gdbsupport/gdb_optional.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>> gdbsupport/gdb_unique_ptr.h:#if __cplusplus >= 201402L
>> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>> $ find gdb* -type f \
>> | egrep -v "/configure|\.m4" \
>> | xargs grep "# *if.*__cplusplus.*2017"
>> gdb/unittests/string_view-selftests.c:#if __cplusplus < 201703L
>> gdb/disasm.h:#if __cplusplus >= 201703L
>> gdbsupport/invoke-result.h:#if __cplusplus >= 201703L
>> gdbsupport/gdb_string_view.h:#if __cplusplus >= 201703L
>> ...
>> but that's not yet included in this patch.
>
> If this patch is accepted, one change I'd like is to do is drop
> gdb::make_unique, because 1) the current fallback we have for C++11
> compilers is not entirely compatible with std::make_unique (the T[] case
> is not supported properly I think), and 2) it is not widely used yet, so
> "it's not too late" :D
For my own education, is there something which we can write using
gdb::make_unique, which compiles, and does something useful, but which
isn't supported with std::make_unique?
Or something that behaves differently with std::make_unique vs
gdb::make_unique?
You mention the T[] case isn't supported, but that doesn't feel like
something we might be "too late" for -- that would just mean when we
switch to std::make_unique we can do more...
Thanks,
Andrew
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH RFC] Require c++17 compiler
2023-10-05 12:26 ` Andrew Burgess
@ 2023-10-05 14:26 ` Lancelot SIX
2023-10-05 14:32 ` Simon Marchi
0 siblings, 1 reply; 14+ messages in thread
From: Lancelot SIX @ 2023-10-05 14:26 UTC (permalink / raw)
To: Andrew Burgess, Tom de Vries; +Cc: gdb-patches
On 05/10/2023 13:26, Andrew Burgess wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> Lancelot SIX via Gdb-patches <gdb-patches@sourceware.org> writes:
>
>> Hi Tom,
>>
>> Thanks for putting this together! As you know, I am in favor of such
>> change (for GDB-15 probably, GDB-14 branching is probably too close)!
>>
>> I do have a really similar patch available on a local branch. One
>> difference though is that my branch uses a preparatory patch to upgrade
>> gdb/ax_cxx_compile_stdcxx.m4 to follow upstream changes to this file.
>> This upgrade gives some improvements in the C++17 compiler detection.
>> We keep this in the GDB tree because it has some local changes to set
>> CXX_DIALECT. This preparatory patch should be included in this reply.
>>
>> On Thu, Oct 05, 2023 at 08:54:49AM +0200, Tom de Vries wrote:
>>> Since gdb 8.0, we've required a c++11 compiler.
>>>
>>> That allowed gdb to be compiled with gcc releases as far back as gcc 4.8,
>>> using an explicit -std=c++11 to override the default.
>>>
>>> [ Gcc has the following defaults:
>>> - before gcc 6: c++98, and
>>> - for gcc 6-10: c++14, and
>>> - since gcc 11: c++17. ]
>>>
>>> There are two arguments in favor of moving to requiring a newer c++ standard:
>>> - benefits can be had from using newer c++ features. We're already using some
>>> of those features using gdb-specific implementations.
>>> - when developing gdb on modern platforms with system compiler gcc >= 6,
>>> people can accidentally use c++14/c++17 features in a patch, only to find out
>>> post-commit that it breaks the build on a system with a compiler that only
>>> supports c++11, which is inconvenient and takes time to fix.
>>> [ This could be partially mitigated by if possible also forcing -std=c++11
>>> for such compilers. ]
>>
>> Thanks for pointing this out, this was one trigger for me to start
>> looking into this!
>>
>>>
>>> The need to keep requiring c++11 comes from porting new gdb releases to older
>>> systems with older system compilers.
>>>
>>> A review of some relevant distros has shown that in case that requiring c++17
>>> results in no longer being able to use the system compiler, an alternative,
>>> newer compiler that does support c++17 is readily available.
>>>
>>> With nothing holding back the change, require a c++17 compiler to build gdb.
>>
>> Just for the record, it might be worth mentioning here the general
>> policy of the project regarding bumping the C++ required version:
>> https://sourceware.org/gdb/wiki/Internals%20GDB-C-Coding-Standards#When_is_GDB_going_to_start_requiring_C.2B-.2B-NN_.3F
>>
>>>
>>> The gcc documentation ( https://gcc.gnu.org/projects/cxx-status.html ) states
>>> that "Some C++17 features are available since GCC 5, but support was
>>> experimental and the ABI of C++17 features was not stable until GCC 9".
>>>
>>> Consequently, the NEWS item mentions gcc 9 as an example compiler to use.
>>>
>>> My understanding of using gcc 5-8 is that it works as long as gdb doesn't use
>>> not yet available language features. Of course the set of used language
>>> features may change in time, so what compiler still works may change.
>>>
>>> Problems can arise when shared libs starts to have C++17 based APIs (or
>>> somehow expose instantiations of such classes). If compiled with a compiler
>>> in which c++17 support was still experimental, it may be incompatible when
>>> linking with:
>>> - code compiled with a compiler with non-experimental c++17 support, or
>>> - code compiled with a different compiler with experimental c++17 support.
>>>
>>> Looking at the current implementation of our only shared lib:
>>> libinproctrace.so, I couldn't spot any c++ usage in the API, so I'm assuming
>>> this problem is not likely to happen.
>>>
>>> Requiring c++17 means we can drop some code:
>>> ...
>>> $ find gdb* -type f \
>>> | egrep -v "/configure|\.m4" \
>>> | xargs grep "# *if.*__cplusplus.*2014"
>>> gdb/cp-support.c:#if __cplusplus >= 201402L
>>> gdb/dwarf2/cooked-index.c:#if __cplusplus >= 201402L
>>> gdbsupport/gdb_optional.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>>> gdbsupport/gdb_optional.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>>> gdbsupport/gdb_unique_ptr.h:#if __cplusplus >= 201402L
>>> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>>> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>>> gdbsupport/array-view.h:#if defined(_GLIBCXX_DEBUG) && __cplusplus >= 201402L
>>> $ find gdb* -type f \
>>> | egrep -v "/configure|\.m4" \
>>> | xargs grep "# *if.*__cplusplus.*2017"
>>> gdb/unittests/string_view-selftests.c:#if __cplusplus < 201703L
>>> gdb/disasm.h:#if __cplusplus >= 201703L
>>> gdbsupport/invoke-result.h:#if __cplusplus >= 201703L
>>> gdbsupport/gdb_string_view.h:#if __cplusplus >= 201703L
>>> ...
>>> but that's not yet included in this patch.
>>
>> If this patch is accepted, one change I'd like is to do is drop
>> gdb::make_unique, because 1) the current fallback we have for C++11
>> compilers is not entirely compatible with std::make_unique (the T[] case
>> is not supported properly I think), and 2) it is not widely used yet, so
>> "it's not too late" :D
>
> For my own education, is there something which we can write using
> gdb::make_unique, which compiles, and does something useful, but which
> isn't supported with std::make_unique >
> Or something that behaves differently with std::make_unique vs
> gdb::make_unique?
>
> You mention the T[] case isn't supported, but that doesn't feel like
> something we might be "too late" for -- that would just mean when we
> switch to std::make_unique we can do more...
Hi Andrew
I don't think something like gdb::make_unique<int[]>(2) would compile
with a c++11 compiler. So I don't expect that a given statement would
compile fine in both C++11 and C++17 but with different semantics.
The difference can be fixed, we can have a complete implementation with
c++11. It is just that the current state of things, gdb::make_unique is
not 100% equivalent to std::make_unique.
By "not too late", I mean that we currently have ~20 places using
gdb::make_unique. It is still easy to replace them all and just use the
standard library if available. If we have a standard version, I don't
see the point in keeping the gdb:: version.
If you take something like gdb::optional for example, it is used quite
extensively in the codebase, and I don't think it would be easy to
remove the it in favor of the standard C++ version any time soon. We
can have gdb::optional be an alias to std::optional, but the codebase
will still continue to use "gdb::optional" independently of how this is
implemented.
I hope that this clarifies my position regarding gdb::make_unique.
Best,
Lancelot.
>
> Thanks,
> Andrew
>
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH RFC] Require c++17 compiler
2023-10-05 14:26 ` Lancelot SIX
@ 2023-10-05 14:32 ` Simon Marchi
2023-10-05 14:55 ` Lancelot SIX
2023-10-05 15:55 ` Tom Tromey
0 siblings, 2 replies; 14+ messages in thread
From: Simon Marchi @ 2023-10-05 14:32 UTC (permalink / raw)
To: Lancelot SIX, Andrew Burgess, Tom de Vries; +Cc: gdb-patches
On 10/5/23 10:26, Lancelot SIX via Gdb-patches wrote:
> If you take something like gdb::optional for example, it is used quite
> extensively in the codebase, and I don't think it would be easy to
> remove the it in favor of the standard C++ version any time soon. We
> can have gdb::optional be an alias to std::optional, but the codebase
> will still continue to use "gdb::optional" independently of how this
> is implemented.
Wouldn't it be a simple find and replace, gdb::optional to
std::optional? Conveniently, it's the same number of characters, so it
doesn't even affect line-wrapping.
Simon
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH RFC] Require c++17 compiler
2023-10-05 14:32 ` Simon Marchi
@ 2023-10-05 14:55 ` Lancelot SIX
2023-10-09 14:32 ` Andrew Burgess
2023-10-05 15:55 ` Tom Tromey
1 sibling, 1 reply; 14+ messages in thread
From: Lancelot SIX @ 2023-10-05 14:55 UTC (permalink / raw)
To: Simon Marchi, Andrew Burgess, Tom de Vries; +Cc: gdb-patches
>
> Wouldn't it be a simple find and replace, gdb::optional to
> std::optional? Conveniently, it's the same number of characters, so it
> doesn't even affect line-wrapping.
>
> Simon
I guess it is mostly true, there could be some cases where one can do
namespace gdb {
optional<Foo> f;
}
But I really don't think we have many of such occurrences.
So in the end, I agree that that is a viable option with a big-ish patch.
Best,
Lancelot.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [RFC] [gdb/build] Require c++17 compiler
2023-10-05 6:54 [RFC] [gdb/build] Require c++17 compiler Tom de Vries
2023-10-05 10:33 ` [PATCH RFC] " Lancelot SIX
@ 2023-10-05 15:31 ` Tom Tromey
2023-10-10 17:39 ` Tom Tromey
2023-10-12 17:10 ` Pedro Alves
2023-10-12 17:22 ` Pedro Alves
3 siblings, 1 reply; 14+ messages in thread
From: Tom Tromey @ 2023-10-05 15:31 UTC (permalink / raw)
To: Tom de Vries via Gdb-patches; +Cc: Tom de Vries
>>>>> "Tom" == Tom de Vries via Gdb-patches <gdb-patches@sourceware.org> writes:
Tom> A review of some relevant distros has shown that in case that requiring c++17
Tom> results in no longer being able to use the system compiler, an alternative,
Tom> newer compiler that does support c++17 is readily available.
Tom> With nothing holding back the change, require a c++17 compiler to build gdb.
I'm in favor of the change.
IIRC the current rule is that gdb shouldn't rely on anything newer than
3 years old (?) and furthermore that the required compiler should either
be in the major distros' active LTS releases, or readily installable
there. Since you've looked into this, I think we're fine to move
forward.
However, I do agree with Lancelot that we should do this in GDB 15.
That is, hold this patch and land it on trunk shortly after the branch
is made.
thanks,
Tom
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH RFC] Require c++17 compiler
2023-10-05 14:32 ` Simon Marchi
2023-10-05 14:55 ` Lancelot SIX
@ 2023-10-05 15:55 ` Tom Tromey
1 sibling, 0 replies; 14+ messages in thread
From: Tom Tromey @ 2023-10-05 15:55 UTC (permalink / raw)
To: Simon Marchi via Gdb-patches
Cc: Lancelot SIX, Andrew Burgess, Tom de Vries, Simon Marchi
>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
Simon> On 10/5/23 10:26, Lancelot SIX via Gdb-patches wrote:
>> If you take something like gdb::optional for example, it is used quite
>> extensively in the codebase, and I don't think it would be easy to
>> remove the it in favor of the standard C++ version any time soon. We
>> can have gdb::optional be an alias to std::optional, but the codebase
>> will still continue to use "gdb::optional" independently of how this
>> is implemented.
Simon> Wouldn't it be a simple find and replace, gdb::optional to
Simon> std::optional? Conveniently, it's the same number of characters, so it
Simon> doesn't even affect line-wrapping.
I wrote a patch to make gdb_optional.h check __cplusplus and use the
C++17 std::optional. I had to comment out some of the test code to get
it to compile (warnings about set-but-unused variables), but other than
that it seems fine. I'm running the test suite now.
Tom
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH RFC] Require c++17 compiler
2023-10-05 14:55 ` Lancelot SIX
@ 2023-10-09 14:32 ` Andrew Burgess
0 siblings, 0 replies; 14+ messages in thread
From: Andrew Burgess @ 2023-10-09 14:32 UTC (permalink / raw)
To: Lancelot SIX, Simon Marchi, Tom de Vries; +Cc: gdb-patches
Lancelot SIX <Lancelot.Six@amd.com> writes:
>>
>> Wouldn't it be a simple find and replace, gdb::optional to
>> std::optional? Conveniently, it's the same number of characters, so it
>> doesn't even affect line-wrapping.
>>
>> Simon
>
> I guess it is mostly true, there could be some cases where one can do
>
> namespace gdb {
> optional<Foo> f;
> }
>
> But I really don't think we have many of such occurrences.
>
> So in the end, I agree that that is a viable option with a big-ish patch.
I agree with Simon; when we move to C++17 we'll just rip out
gdb::optional and have one big patch to move us to std::optional. I
don't see this as a problem.
We can easily do the same with gdb::make_unique too.
Hopefully once GDB 14 releases, we can go ahead and move to C++17 so
this issue will resolve itself.
Thanks,
Andrew
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [RFC] [gdb/build] Require c++17 compiler
2023-10-05 15:31 ` [RFC] [gdb/build] " Tom Tromey
@ 2023-10-10 17:39 ` Tom Tromey
2023-10-10 19:16 ` Simon Marchi
0 siblings, 1 reply; 14+ messages in thread
From: Tom Tromey @ 2023-10-10 17:39 UTC (permalink / raw)
To: Tom Tromey; +Cc: Tom de Vries via Gdb-patches, Tom de Vries
>>>>> "Tom" == Tom Tromey <tom@tromey.com> writes:
Tom> However, I do agree with Lancelot that we should do this in GDB 15.
Tom> That is, hold this patch and land it on trunk shortly after the branch
Tom> is made.
GDB 14 has branched, so I think this would be a good time to switch to
C++17 on trunk.
thanks,
Tom
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [RFC] [gdb/build] Require c++17 compiler
2023-10-10 17:39 ` Tom Tromey
@ 2023-10-10 19:16 ` Simon Marchi
0 siblings, 0 replies; 14+ messages in thread
From: Simon Marchi @ 2023-10-10 19:16 UTC (permalink / raw)
To: Tom Tromey; +Cc: Tom de Vries via Gdb-patches, Tom de Vries
On 10/10/23 13:39, Tom Tromey wrote:
>>>>>> "Tom" == Tom Tromey <tom@tromey.com> writes:
>
> Tom> However, I do agree with Lancelot that we should do this in GDB 15.
> Tom> That is, hold this patch and land it on trunk shortly after the branch
> Tom> is made.
>
> GDB 14 has branched, so I think this would be a good time to switch to
> C++17 on trunk.
Agreed, go go go!
We just need to be mindful when backporting patches from master to
gdb-14-branch, that they work with C++11.
Simon
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [RFC] [gdb/build] Require c++17 compiler
2023-10-05 6:54 [RFC] [gdb/build] Require c++17 compiler Tom de Vries
2023-10-05 10:33 ` [PATCH RFC] " Lancelot SIX
2023-10-05 15:31 ` [RFC] [gdb/build] " Tom Tromey
@ 2023-10-12 17:10 ` Pedro Alves
2023-10-12 17:22 ` Pedro Alves
3 siblings, 0 replies; 14+ messages in thread
From: Pedro Alves @ 2023-10-12 17:10 UTC (permalink / raw)
To: Tom de Vries, gdb-patches
On 2023-10-05 07:54, Tom de Vries via Gdb-patches wrote:
> Since gdb 8.0, we've required a c++11 compiler.
>
> That allowed gdb to be compiled with gcc releases as far back as gcc 4.8,
> using an explicit -std=c++11 to override the default.
>
> [ Gcc has the following defaults:
> - before gcc 6: c++98, and
> - for gcc 6-10: c++14, and
> - since gcc 11: c++17. ]
>
Just a comment here:
> There are two arguments in favor of moving to requiring a newer c++ standard:
> - benefits can be had from using newer c++ features. We're already using some
> of those features using gdb-specific implementations.
...
> - when developing gdb on modern platforms with system compiler gcc >= 6,
> people can accidentally use c++14/c++17 features in a patch, only to find out
> post-commit that it breaks the build on a system with a compiler that only
> supports c++11, which is inconvenient and takes time to fix.
> [ This could be partially mitigated by if possible also forcing -std=c++11
> for such compilers. ]
Whether to force -std=c++11 to avoid this had been discussed back in the C++11
transition as well, and we decided against back then. The benefit of being able to
conditionally use newer C++ features, which may e.g., be a lot more efficient,
or the making sure our replacements don't deviate from actual standard components
(by actually using them when possible), outweighs the rare breakage concern, IMHO.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [RFC] [gdb/build] Require c++17 compiler
2023-10-05 6:54 [RFC] [gdb/build] Require c++17 compiler Tom de Vries
` (2 preceding siblings ...)
2023-10-12 17:10 ` Pedro Alves
@ 2023-10-12 17:22 ` Pedro Alves
3 siblings, 0 replies; 14+ messages in thread
From: Pedro Alves @ 2023-10-12 17:22 UTC (permalink / raw)
To: Tom de Vries, gdb-patches
On 2023-10-05 07:54, Tom de Vries via Gdb-patches wrote:
> Consequently, the NEWS item mentions gcc 9 as an example compiler to use.
>
> My understanding of using gcc 5-8 is that it works as long as gdb doesn't use
> not yet available language features. Of course the set of used language
> features may change in time, so what compiler still works may change.
>
> Problems can arise when shared libs starts to have C++17 based APIs (or
> somehow expose instantiations of such classes). If compiled with a compiler
> in which c++17 support was still experimental, it may be incompatible when
> linking with:
> - code compiled with a compiler with non-experimental c++17 support, or
> - code compiled with a different compiler with experimental c++17 support.
>
> Looking at the current implementation of our only shared lib:
> libinproctrace.so, I couldn't spot any c++ usage in the API, so I'm assuming
> this problem is not likely to happen.
I think this concern goes beyond libinproctrace.co, and extends to APIs exposed
by libstdc++. E.g., (and I haven't checked), say that the libstdc++ from GCC 6
implemented some C++17 library feature that we start using, but then the API/ABI of
that library feature changed in later GCCs. Compiling GDB with GCC 6 and
expecting that it runs on a system with libstdc++ from GCC 9 may not work. I don't
know whether there's some document or page or wiki or some such somewhere documenting
such ABI breakages. +1 on requiring GCC 9, unless it proves troublesomely "too new"
in practice, which I hope not.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH RFC] Require c++17 compiler
2023-10-05 10:33 ` [PATCH RFC] " Lancelot SIX
2023-10-05 12:26 ` Andrew Burgess
@ 2023-10-12 17:30 ` Pedro Alves
1 sibling, 0 replies; 14+ messages in thread
From: Pedro Alves @ 2023-10-12 17:30 UTC (permalink / raw)
To: Lancelot SIX, Tom de Vries; +Cc: gdb-patches
On 2023-10-05 11:33, Lancelot SIX via Gdb-patches wrote:
> Hi Tom,
>
> Thanks for putting this together! As you know, I am in favor of such
> change (for GDB-15 probably, GDB-14 branching is probably too close)!
>
> I do have a really similar patch available on a local branch. One
> difference though is that my branch uses a preparatory patch to upgrade
> gdb/ax_cxx_compile_stdcxx.m4 to follow upstream changes to this file.
> This upgrade gives some improvements in the C++17 compiler detection.
> We keep this in the GDB tree because it has some local changes to set
> CXX_DIALECT. This preparatory patch should be included in this reply.
>
(As discussed at the Cauldron,) I agree it would be nice to do that, either
before or after the C++17 requirement change. Your attached patch looks fine to me.
^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2023-10-12 17:30 UTC | newest]
Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-10-05 6:54 [RFC] [gdb/build] Require c++17 compiler Tom de Vries
2023-10-05 10:33 ` [PATCH RFC] " Lancelot SIX
2023-10-05 12:26 ` Andrew Burgess
2023-10-05 14:26 ` Lancelot SIX
2023-10-05 14:32 ` Simon Marchi
2023-10-05 14:55 ` Lancelot SIX
2023-10-09 14:32 ` Andrew Burgess
2023-10-05 15:55 ` Tom Tromey
2023-10-12 17:30 ` Pedro Alves
2023-10-05 15:31 ` [RFC] [gdb/build] " Tom Tromey
2023-10-10 17:39 ` Tom Tromey
2023-10-10 19:16 ` Simon Marchi
2023-10-12 17:10 ` Pedro Alves
2023-10-12 17:22 ` Pedro Alves
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