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* [gcc r13-8429] libstdc++: Implement P2905R2 "Runtime format strings" for C++20
@ 2024-03-12 14:17 Jonathan Wakely
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From: Jonathan Wakely @ 2024-03-12 14:17 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:3c8faeac3d03e032d55fae390618e577c292a83e
commit r13-8429-g3c8faeac3d03e032d55fae390618e577c292a83e
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Sun Jan 7 22:21:08 2024 +0000
libstdc++: Implement P2905R2 "Runtime format strings" for C++20
This change makes std::make_format_args refuse to create dangling
references to temporaries. This makes the std::vformat API safer. This
was approved in Kona 2023 as a DR for C++20 so the change is implemented
unconditionally.
libstdc++-v3/ChangeLog:
* include/bits/chrono_io.h (__formatter_chrono): Always use
lvalue arguments to make_format_args.
* include/std/format (make_format_args): Change parameter pack
from forwarding references to lvalue references. Remove use of
remove_reference_t which is now unnecessary.
(format_to, formatted_size): Remove incorrect forwarding of
arguments.
* testsuite/20_util/duration/io.cc: Use lvalues as arguments to
make_format_args.
* testsuite/std/format/arguments/args.cc: Likewise.
* testsuite/std/format/arguments/lwg3810.cc: Likewise.
* testsuite/std/format/functions/format.cc: Likewise.
* testsuite/std/format/functions/vformat_to.cc: Likewise.
* testsuite/std/format/string.cc: Likewise.
* testsuite/std/time/day/io.cc: Likewise.
* testsuite/std/time/month/io.cc: Likewise.
* testsuite/std/time/weekday/io.cc: Likewise.
* testsuite/std/time/year/io.cc: Likewise.
* testsuite/std/time/year_month_day/io.cc: Likewise.
* testsuite/std/format/arguments/args_neg.cc: New test.
(cherry picked from commit 2a8ee2592e48735d88df786cbafa6b0da39fc4d6)
Diff:
---
libstdc++-v3/include/bits/chrono_io.h | 15 +++++++----
libstdc++-v3/include/std/format | 30 +++++++++++-----------
libstdc++-v3/testsuite/20_util/duration/io.cc | 3 ++-
.../testsuite/std/format/arguments/args.cc | 26 ++++++++++++++-----
.../testsuite/std/format/arguments/args_neg.cc | 12 +++++++++
.../testsuite/std/format/arguments/lwg3810.cc | 8 ++++--
.../testsuite/std/format/functions/format.cc | 6 +++--
.../testsuite/std/format/functions/vformat_to.cc | 9 +++++--
libstdc++-v3/testsuite/std/format/string.cc | 7 +++--
libstdc++-v3/testsuite/std/time/day/io.cc | 4 +--
libstdc++-v3/testsuite/std/time/month/io.cc | 4 +--
libstdc++-v3/testsuite/std/time/weekday/io.cc | 4 +--
libstdc++-v3/testsuite/std/time/year/io.cc | 4 +--
.../testsuite/std/time/year_month_day/io.cc | 4 +--
14 files changed, 91 insertions(+), 45 deletions(-)
diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h
index c42797f64c4..1c08130bf65 100644
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -2195,7 +2195,8 @@ namespace chrono
_Str __s = _GLIBCXX_WIDEN("{:02d} is not a valid day");
if (__d.ok())
__s = __s.substr(0, 6);
- __os << std::vformat(__s, make_format_args<_Ctx>((unsigned)__d));
+ auto __u = (unsigned)__d;
+ __os << std::vformat(__s, make_format_args<_Ctx>(__u));
return __os;
}
@@ -2213,8 +2214,10 @@ namespace chrono
__os << std::vformat(__os.getloc(), __s.substr(0, 6),
make_format_args<_Ctx>(__m));
else
- __os << std::vformat(__s.substr(6),
- make_format_args<_Ctx>((unsigned)__m));
+ {
+ auto __u = (unsigned)__m;
+ __os << std::vformat(__s.substr(6), make_format_args<_Ctx>(__u));
+ }
return __os;
}
@@ -2253,8 +2256,10 @@ namespace chrono
__os << std::vformat(__os.getloc(), __s.substr(0, 6),
make_format_args<_Ctx>(__wd));
else
- __os << std::vformat(__s.substr(6),
- make_format_args<_Ctx>(__wd.c_encoding()));
+ {
+ auto __c = __wd.c_encoding();
+ __os << std::vformat(__s.substr(6), make_format_args<_Ctx>(__c));
+ }
return __os;
}
diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 807c97680c6..7bcaddb3715 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -3117,7 +3117,7 @@ namespace __format
template<typename _Ctx, typename... _Argz>
friend auto
- make_format_args(_Argz&&...) noexcept;
+ make_format_args(_Argz&...) noexcept;
template<typename _Visitor, typename _Ctx>
friend decltype(auto)
@@ -3287,7 +3287,7 @@ namespace __format
template<typename _Ctx, typename... _Args>
friend auto
- make_format_args(_Args&&...) noexcept;
+ make_format_args(_Args&...) noexcept;
// An array of _Arg_t enums corresponding to _Args...
template<typename... _Args>
@@ -3325,7 +3325,7 @@ namespace __format
template<typename _Context, typename... _Args>
auto
- make_format_args(_Args&&... __fmt_args) noexcept;
+ make_format_args(_Args&... __fmt_args) noexcept;
// An array of type-erased formatting arguments.
template<typename _Context, typename... _Args>
@@ -3338,7 +3338,7 @@ namespace __format
#if _GLIBCXX_INLINE_VERSION
__8:: // Needed for PR c++/59256
#endif
- make_format_args(_Argz&&...) noexcept;
+ make_format_args(_Argz&...) noexcept;
// For a sufficiently small number of arguments we only store values.
// basic_format_args can get the types from the _Args pack.
@@ -3412,11 +3412,11 @@ namespace __format
template<typename _Context = format_context, typename... _Args>
[[nodiscard,__gnu__::__always_inline__]]
inline auto
- make_format_args(_Args&&... __fmt_args) noexcept
+ make_format_args(_Args&... __fmt_args) noexcept
{
using _Fmt_arg = basic_format_arg<_Context>;
using _Store = __format::_Arg_store<_Context, typename _Fmt_arg::template
- _Normalize<remove_reference_t<_Args>>...>;
+ _Normalize<_Args>...>;
return _Store(__fmt_args...);
}
@@ -3424,7 +3424,7 @@ namespace __format
template<typename... _Args>
[[nodiscard,__gnu__::__always_inline__]]
inline auto
- make_wformat_args(_Args&&... __args) noexcept
+ make_wformat_args(_Args&... __args) noexcept
{ return std::make_format_args<wformat_context>(__args...); }
/// @cond undocumented
@@ -3857,7 +3857,7 @@ namespace __format
format_to(_Out __out, format_string<_Args...> __fmt, _Args&&... __args)
{
return std::vformat_to(std::move(__out), __fmt.get(),
- std::make_format_args(std::forward<_Args>(__args)...));
+ std::make_format_args(__args...));
}
template<typename _Out, typename... _Args>
@@ -3866,7 +3866,7 @@ namespace __format
format_to(_Out __out, wformat_string<_Args...> __fmt, _Args&&... __args)
{
return std::vformat_to(std::move(__out), __fmt.get(),
- std::make_wformat_args(std::forward<_Args>(__args)...));
+ std::make_wformat_args(__args...));
}
template<typename _Out, typename... _Args>
@@ -3876,7 +3876,7 @@ namespace __format
_Args&&... __args)
{
return std::vformat_to(std::move(__out), __loc, __fmt.get(),
- std::make_format_args(std::forward<_Args>(__args)...));
+ std::make_format_args(__args...));
}
template<typename _Out, typename... _Args>
@@ -3886,7 +3886,7 @@ namespace __format
_Args&&... __args)
{
return std::vformat_to(std::move(__out), __loc, __fmt.get(),
- std::make_wformat_args(std::forward<_Args>(__args)...));
+ std::make_wformat_args(__args...));
}
template<typename _Out, typename... _Args>
@@ -3988,7 +3988,7 @@ namespace __format
{
__format::_Counting_sink<char> __buf;
std::vformat_to(__buf.out(), __fmt.get(),
- std::make_format_args(std::forward<_Args>(__args)...));
+ std::make_format_args(__args...));
return __buf.count();
}
@@ -3999,7 +3999,7 @@ namespace __format
{
__format::_Counting_sink<wchar_t> __buf;
std::vformat_to(__buf.out(), __fmt.get(),
- std::make_wformat_args(std::forward<_Args>(__args)...));
+ std::make_wformat_args(__args...));
return __buf.count();
}
@@ -4011,7 +4011,7 @@ namespace __format
{
__format::_Counting_sink<char> __buf;
std::vformat_to(__buf.out(), __loc, __fmt.get(),
- std::make_format_args(std::forward<_Args>(__args)...));
+ std::make_format_args(__args...));
return __buf.count();
}
@@ -4023,7 +4023,7 @@ namespace __format
{
__format::_Counting_sink<wchar_t> __buf;
std::vformat_to(__buf.out(), __loc, __fmt.get(),
- std::make_wformat_args(std::forward<_Args>(__args)...));
+ std::make_wformat_args(__args...));
return __buf.count();
}
diff --git a/libstdc++-v3/testsuite/20_util/duration/io.cc b/libstdc++-v3/testsuite/20_util/duration/io.cc
index 5f0f25eac69..2043f0c4e9d 100644
--- a/libstdc++-v3/testsuite/20_util/duration/io.cc
+++ b/libstdc++-v3/testsuite/20_util/duration/io.cc
@@ -83,7 +83,8 @@ test_format()
char fmt[] = { '{', ':', '%', c, '}' };
try
{
- (void) std::vformat(std::string_view(fmt, 5), std::make_format_args(1s));
+ auto s = 1s;
+ (void) std::vformat(std::string_view(fmt, 5), std::make_format_args(s));
// The call above should throw for any conversion-spec not in my_specs:
VERIFY(my_specs.find(c) != my_specs.npos);
}
diff --git a/libstdc++-v3/testsuite/std/format/arguments/args.cc b/libstdc++-v3/testsuite/std/format/arguments/args.cc
index ae2eab6d560..e2e7a3e7ee5 100644
--- a/libstdc++-v3/testsuite/std/format/arguments/args.cc
+++ b/libstdc++-v3/testsuite/std/format/arguments/args.cc
@@ -47,7 +47,12 @@ struct std::formatter<E> : std::formatter<int>
void
test_args()
{
- auto store = std::make_format_args(false, 1, '2', 3.4);
+ bool b = false;
+ int i = 1;
+ char c = '2';
+ double d = 3.4;
+
+ auto store = std::make_format_args(b, i, c, d);
std::format_args args = store;
VERIFY(equals(args.get(0), false));
VERIFY(equals(args.get(1), 1));
@@ -55,7 +60,11 @@ test_args()
VERIFY(equals(args.get(3), 3.4));
VERIFY(!args.get(4));
- auto cstore = std::make_format_args<std::format_context>(5L, 6ULL, 7.8f);
+ long l = 5L;
+ unsigned long long ull = 6ULL;
+ float f = 7.8f;
+
+ auto cstore = std::make_format_args<std::format_context>(l, ull, f);
std::format_args cargs = cstore;
if constexpr (sizeof(long) == sizeof(int))
VERIFY(equals(cargs.get(0), 5));
@@ -65,14 +74,17 @@ test_args()
VERIFY(equals(cargs.get(2), 7.8f));
VERIFY(!cargs.get(3));
- VERIFY(equals(std::format_args(std::make_format_args(std::string("tenfour"))).get(0), std::string_view("tenfour")));
+ std::string s = "tenfour";
+ VERIFY(equals(std::format_args(std::make_format_args(s)).get(0), std::string_view("tenfour")));
+ char nine = '9';
+ wchar_t ten = L'X';
// This needs to be on the stack so that testing pointer equality works.
wchar_t eleven[] = L"eleven";
- // This needs to be on the stack so that the wstring_view doesn't dangle.
+ long double twelve13 = 12.13L;
std::wstring tenfour = L"tenfour";
- auto wstore = std::make_wformat_args('9', L'X', eleven, 12.13L, tenfour);
+ auto wstore = std::make_wformat_args(nine, ten, eleven, twelve13, tenfour);
std::wformat_args wargs = wstore;
VERIFY(equals(wargs.get(0), static_cast<wchar_t>('9')));
VERIFY(equals(wargs.get(1), L'X'));
@@ -81,7 +93,9 @@ test_args()
VERIFY(equals(wargs.get(4), std::wstring_view(tenfour)));
VERIFY(!wargs.get(5));
- auto another_store = std::make_format_args(nullptr, E::ByGum);
+ std::nullptr_t null;
+ E eebygum = E::ByGum;
+ auto another_store = std::make_format_args(null, eebygum);
args = another_store;
VERIFY(equals(args.get(0), static_cast<const void*>(nullptr)));
using handle = std::basic_format_arg<std::format_context>::handle;
diff --git a/libstdc++-v3/testsuite/std/format/arguments/args_neg.cc b/libstdc++-v3/testsuite/std/format/arguments/args_neg.cc
new file mode 100644
index 00000000000..16ac3040146
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/format/arguments/args_neg.cc
@@ -0,0 +1,12 @@
+// { dg-do compile { target c++20 } }
+
+// P2905R2 Runtime format strings
+
+#include <format>
+
+std::string rval() { return "path/etic/experience"; }
+
+void f()
+{
+ (void)std::make_format_args(rval()); // { dg-error "cannot bind non-const lvalue reference" }
+}
diff --git a/libstdc++-v3/testsuite/std/format/arguments/lwg3810.cc b/libstdc++-v3/testsuite/std/format/arguments/lwg3810.cc
index 9ccb654de1b..df3d98e33f7 100644
--- a/libstdc++-v3/testsuite/std/format/arguments/lwg3810.cc
+++ b/libstdc++-v3/testsuite/std/format/arguments/lwg3810.cc
@@ -5,7 +5,11 @@
#include <format>
-auto args_store = std::make_format_args(1,2,3);
+int x = 1;
+long y = 2;
+short z = 3;
+
+auto args_store = std::make_format_args(x, y, z);
std::basic_format_args args = args_store;
static_assert(std::is_same_v<decltype(args), std::format_args>);
@@ -21,5 +25,5 @@ test_ctad()
using SomeContext = std::wformat_context;
// foo(make_format_args<SomeContext>(...)); // won't work
- foo(basic_format_args(make_format_args<SomeContext>(1, 2, 3))); // should work
+ foo(basic_format_args(make_format_args<SomeContext>(x, y, z))); // should work
}
diff --git a/libstdc++-v3/testsuite/std/format/functions/format.cc b/libstdc++-v3/testsuite/std/format/functions/format.cc
index 531b6a312d7..1f1802e561c 100644
--- a/libstdc++-v3/testsuite/std/format/functions/format.cc
+++ b/libstdc++-v3/testsuite/std/format/functions/format.cc
@@ -261,14 +261,16 @@ test_width()
}
try {
- auto args = std::make_format_args(false, true);
+ bool no = false, yes = true;
+ auto args = std::make_format_args(no, yes);
s = std::vformat("DR 3720: restrict type of width arg-id {0:{1}}", args);
VERIFY(false);
} catch (const std::format_error&) {
}
try {
- auto args = std::make_format_args('?', '!');
+ char wat = '?', bang = '!';
+ auto args = std::make_format_args(wat, bang);
s = std::vformat("DR 3720: restrict type of width arg-id {0:{1}}", args);
VERIFY(false);
} catch (const std::format_error&) {
diff --git a/libstdc++-v3/testsuite/std/format/functions/vformat_to.cc b/libstdc++-v3/testsuite/std/format/functions/vformat_to.cc
index 6fa33b9fbac..320914e272a 100644
--- a/libstdc++-v3/testsuite/std/format/functions/vformat_to.cc
+++ b/libstdc++-v3/testsuite/std/format/functions/vformat_to.cc
@@ -30,17 +30,22 @@ private:
void
test_move_only()
{
+ const char arg1[] = "matte";
+ int arg2 = '!';
+
std::string str;
move_only_iterator<char> mo(std::back_inserter(str));
auto res = std::vformat_to(std::move(mo), "for{:.3} that{:c}",
- std::make_format_args("matte", (int)'!'));
+ std::make_format_args(arg1, arg2));
static_assert(std::is_same_v<decltype(res), decltype(mo)>);
VERIFY( str == "format that!" );
+ const wchar_t warg1[] = L"matte";
+ long warg2 = L'!';
std::wstring wstr;
move_only_iterator<wchar_t> wmo(std::back_inserter(wstr));
auto wres = std::vformat_to(std::move(wmo), L"for{:.3} that{:c}",
- std::make_wformat_args(L"matte", (long)L'!'));
+ std::make_wformat_args(warg1, warg2));
static_assert(std::is_same_v<decltype(wres), decltype(wmo)>);
VERIFY( wstr == L"format that!" );
}
diff --git a/libstdc++-v3/testsuite/std/format/string.cc b/libstdc++-v3/testsuite/std/format/string.cc
index d70a2331645..a0c07c49f68 100644
--- a/libstdc++-v3/testsuite/std/format/string.cc
+++ b/libstdc++-v3/testsuite/std/format/string.cc
@@ -150,8 +150,9 @@ void
test_pr110862()
{
try {
+ int i = 1;
// PR libstdc++/110862 out-of-bounds read on invalid format string
- (void) std::vformat("{0:{0}", std::make_format_args(1));
+ (void) std::vformat("{0:{0}", std::make_format_args(i));
VERIFY( false );
} catch (const std::format_error& e) {
std::string_view what = e.what();
@@ -163,9 +164,11 @@ void
test_pr110974()
{
try {
+ double d = 1.0;
+ int i = 1;
// PR libstdc++/110974 out of bounds read on invalid format string "{:{}."
std::string_view fmt{"{:{}.0", 5}; // "0" is not part of the format string.
- (void) std::vformat(fmt, std::make_format_args(1.0, 1));
+ (void) std::vformat(fmt, std::make_format_args(d, i));
VERIFY( false );
} catch (const std::format_error& e) {
std::string_view what = e.what();
diff --git a/libstdc++-v3/testsuite/std/time/day/io.cc b/libstdc++-v3/testsuite/std/time/day/io.cc
index b6da0701f98..592ecbb7216 100644
--- a/libstdc++-v3/testsuite/std/time/day/io.cc
+++ b/libstdc++-v3/testsuite/std/time/day/io.cc
@@ -52,8 +52,8 @@ test_format()
char fmt[] = { '{', ':', '%', c, '}' };
try
{
- (void) std::vformat(std::string_view(fmt, 5),
- std::make_format_args(day(1)));
+ day d(1);
+ (void) std::vformat(std::string_view(fmt, 5), std::make_format_args(d));
// The call above should throw for any conversion-spec not in my_specs:
VERIFY(my_specs.find(c) != my_specs.npos);
}
diff --git a/libstdc++-v3/testsuite/std/time/month/io.cc b/libstdc++-v3/testsuite/std/time/month/io.cc
index 59c303bb96c..1f2a4c0e3ce 100644
--- a/libstdc++-v3/testsuite/std/time/month/io.cc
+++ b/libstdc++-v3/testsuite/std/time/month/io.cc
@@ -75,8 +75,8 @@ test_format()
char fmt[] = { '{', ':', '%', c, '}' };
try
{
- (void) std::vformat(std::string_view(fmt, 5),
- std::make_format_args(month(1)));
+ month m(1);
+ (void) std::vformat(std::string_view(fmt, 5), std::make_format_args(m));
// The call above should throw for any conversion-spec not in my_specs:
VERIFY(my_specs.find(c) != my_specs.npos);
}
diff --git a/libstdc++-v3/testsuite/std/time/weekday/io.cc b/libstdc++-v3/testsuite/std/time/weekday/io.cc
index ab213fb559a..3e1661b5052 100644
--- a/libstdc++-v3/testsuite/std/time/weekday/io.cc
+++ b/libstdc++-v3/testsuite/std/time/weekday/io.cc
@@ -78,8 +78,8 @@ test_format()
char fmt[] = { '{', ':', '%', c, '}' };
try
{
- (void) std::vformat(std::string_view(fmt, 5),
- std::make_format_args(weekday(1)));
+ weekday wd(1);
+ (void) std::vformat(std::string_view(fmt, 5), std::make_format_args(wd));
// The call above should throw for any conversion-spec not in my_specs:
VERIFY(my_specs.find(c) != my_specs.npos);
}
diff --git a/libstdc++-v3/testsuite/std/time/year/io.cc b/libstdc++-v3/testsuite/std/time/year/io.cc
index b50d9d89c61..18331deee9c 100644
--- a/libstdc++-v3/testsuite/std/time/year/io.cc
+++ b/libstdc++-v3/testsuite/std/time/year/io.cc
@@ -69,8 +69,8 @@ test_format()
char fmt[] = { '{', ':', '%', c, '}' };
try
{
- (void) std::vformat(std::string_view(fmt, 5),
- std::make_format_args(year(2022)));
+ year y = 2022y;
+ (void) std::vformat(std::string_view(fmt, 5), std::make_format_args(y));
// The call above should throw for any conversion-spec not in my_specs:
VERIFY(my_specs.find(c) != my_specs.npos);
}
diff --git a/libstdc++-v3/testsuite/std/time/year_month_day/io.cc b/libstdc++-v3/testsuite/std/time/year_month_day/io.cc
index 967b4a72406..04e6e59c8f7 100644
--- a/libstdc++-v3/testsuite/std/time/year_month_day/io.cc
+++ b/libstdc++-v3/testsuite/std/time/year_month_day/io.cc
@@ -98,8 +98,8 @@ test_format()
char fmt[] = { '{', ':', '%', c, '}' };
try
{
- (void) std::vformat(std::string_view(fmt, 5),
- std::make_format_args(2022y/December/19));
+ year_month_day ymd = 2022y/December/19;
+ (void) std::vformat(std::string_view(fmt, 5), std::make_format_args(ymd));
// The call above should throw for any conversion-spec not in my_specs:
VERIFY(my_specs.find(c) != my_specs.npos);
}
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