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* [gcc r12-5386] c++: Implement C++23 P0849R8 - auto(x) [PR103049]
@ 2021-11-18 23:01 Marek Polacek
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From: Marek Polacek @ 2021-11-18 23:01 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:93810fd673654db9ff16170624a6d36449eab241
commit r12-5386-g93810fd673654db9ff16170624a6d36449eab241
Author: Marek Polacek <polacek@redhat.com>
Date: Wed Nov 3 11:04:22 2021 -0400
c++: Implement C++23 P0849R8 - auto(x) [PR103049]
This patch implements P0849R8 which allows auto in a functional cast,
the result of which is a prvalue.
[expr.type.conv]/1 says that the type is determined by placeholder type
deduction. We only accept 'auto', not 'decltype(auto)' -- that the
type shall be auto comes from [dcl.type.auto.deduct]. Therefore the
rules are like for [temp.deduct.call], deducing template arguments from
a function call, so the result type will never be a reference, and we
decay arrays/functions.
PR c++/103049
gcc/cp/ChangeLog:
* semantics.c (finish_compound_literal): Accept C++23 auto{x}.
* typeck2.c (build_functional_cast_1): Accept C++23 auto(x).
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/auto25.C: Adjust dg-error.
* g++.dg/cpp0x/auto9.C: Likewise.
* g++.dg/cpp2a/concepts-pr84979-2.C: Likewise.
* g++.dg/cpp2a/concepts-pr84979-3.C: Likewise.
* g++.dg/cpp23/auto-fncast1.C: New test.
* g++.dg/cpp23/auto-fncast2.C: New test.
* g++.dg/cpp23/auto-fncast3.C: New test.
* g++.dg/cpp23/auto-fncast4.C: New test.
* g++.dg/cpp23/auto-fncast5.C: New test.
* g++.dg/cpp23/auto-fncast6.C: New test.
Diff:
---
gcc/cp/semantics.c | 14 ++++++
gcc/cp/typeck2.c | 26 +++++++----
gcc/testsuite/g++.dg/cpp0x/auto25.C | 4 +-
gcc/testsuite/g++.dg/cpp0x/auto9.C | 2 +-
gcc/testsuite/g++.dg/cpp23/auto-fncast1.C | 14 ++++++
gcc/testsuite/g++.dg/cpp23/auto-fncast2.C | 62 +++++++++++++++++++++++++
gcc/testsuite/g++.dg/cpp23/auto-fncast3.C | 21 +++++++++
gcc/testsuite/g++.dg/cpp23/auto-fncast4.C | 26 +++++++++++
gcc/testsuite/g++.dg/cpp23/auto-fncast5.C | 39 ++++++++++++++++
gcc/testsuite/g++.dg/cpp23/auto-fncast6.C | 14 ++++++
gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C | 3 +-
gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C | 3 +-
12 files changed, 215 insertions(+), 13 deletions(-)
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 8f79f047c01..d962b290211 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -3134,6 +3134,20 @@ finish_compound_literal (tree type, tree compound_literal,
if (type == error_mark_node)
return error_mark_node;
}
+ /* C++23 auto{x}. */
+ else if (is_auto (type)
+ && !AUTO_IS_DECLTYPE (type)
+ && CONSTRUCTOR_NELTS (compound_literal) == 1)
+ {
+ if (cxx_dialect < cxx23)
+ pedwarn (input_location, OPT_Wc__23_extensions,
+ "%<auto{x}%> only available with "
+ "%<-std=c++2b%> or %<-std=gnu++2b%>");
+ type = do_auto_deduction (type, compound_literal, type, complain,
+ adc_variable_type);
+ if (type == error_mark_node)
+ return error_mark_node;
+ }
/* Used to hold a copy of the compound literal in a template. */
tree orig_cl = NULL_TREE;
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index e98fbf7f5fa..3fb651a02ba 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -2201,19 +2201,29 @@ build_functional_cast_1 (location_t loc, tree exp, tree parms,
if (tree anode = type_uses_auto (type))
{
- if (!CLASS_PLACEHOLDER_TEMPLATE (anode))
+ tree init;
+ if (CLASS_PLACEHOLDER_TEMPLATE (anode))
+ init = parms;
+ /* C++23 auto(x). */
+ else if (!AUTO_IS_DECLTYPE (anode)
+ && list_length (parms) == 1)
{
- if (complain & tf_error)
- error_at (loc, "invalid use of %qT", anode);
- return error_mark_node;
+ init = TREE_VALUE (parms);
+ if (cxx_dialect < cxx23)
+ pedwarn (loc, OPT_Wc__23_extensions,
+ "%<auto(x)%> only available with "
+ "%<-std=c++2b%> or %<-std=gnu++2b%>");
}
else
{
- type = do_auto_deduction (type, parms, anode, complain,
- adc_variable_type);
- if (type == error_mark_node)
- return error_mark_node;
+ if (complain & tf_error)
+ error_at (loc, "invalid use of %qT", anode);
+ return error_mark_node;
}
+ type = do_auto_deduction (type, init, anode, complain,
+ adc_variable_type);
+ if (type == error_mark_node)
+ return error_mark_node;
}
if (processing_template_decl)
diff --git a/gcc/testsuite/g++.dg/cpp0x/auto25.C b/gcc/testsuite/g++.dg/cpp0x/auto25.C
index 19d51bc8590..3af089958fb 100644
--- a/gcc/testsuite/g++.dg/cpp0x/auto25.C
+++ b/gcc/testsuite/g++.dg/cpp0x/auto25.C
@@ -3,10 +3,10 @@
template<int> struct A
{
- int a[auto(1)]; // { dg-error "9:invalid use of" }
+ int a[auto(1)]; // { dg-error "9:only available" "" { target c++20_down } }
};
template<int> void foo()
{
- int a[auto(1)]; // { dg-error "9:invalid use of" }
+ int a[auto(1)]; // { dg-error "9:only available" "" { target c++20_down } }
}
diff --git a/gcc/testsuite/g++.dg/cpp0x/auto9.C b/gcc/testsuite/g++.dg/cpp0x/auto9.C
index 0e80c30ef74..a3a6caf0a66 100644
--- a/gcc/testsuite/g++.dg/cpp0x/auto9.C
+++ b/gcc/testsuite/g++.dg/cpp0x/auto9.C
@@ -45,7 +45,7 @@ foo ()
C<int> c;
dynamic_cast<auto> (c); // { dg-error "auto" }
reinterpret_cast<auto> (c); // { dg-error "auto" }
- int i = auto (0); // { dg-error "auto" }
+ int i = auto (0); // { dg-error "auto" "" { target c++20_down } }
auto p1 = new (auto); // { dg-error "auto" }
auto p2 = new (auto) (42); // { dg-error "invalid use of|deduce" }
offsetof (auto, fld); // { dg-error "auto" }
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast1.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast1.C
new file mode 100644
index 00000000000..25e53c4d61e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast1.C
@@ -0,0 +1,14 @@
+// PR c++/103049
+// P0849R8 - auto(x)
+// { dg-do compile { target c++23 } }
+// Testcase from P0849R8.
+
+struct A {};
+void f(A&) = delete; // #1
+void f(A&&); // #2
+A& g();
+void h() {
+// f(g()); // calls #1
+ f(A(g())); // calls #2 with a temporary object
+ f(auto(g())); // calls #2 with a temporary object
+}
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast2.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast2.C
new file mode 100644
index 00000000000..327a4480030
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast2.C
@@ -0,0 +1,62 @@
+// PR c++/103049
+// P0849R8 - auto(x)
+// { dg-do compile { target c++23 } }
+
+struct X { };
+X& fn ();
+X&& fnr ();
+
+void h()
+{
+ double v[] = { 1.2, 3.4 };
+ +auto(v);
+ +auto{v};
+ static_assert (__is_same_as (decltype (auto(v)), double *));
+ static_assert (__is_same_as (decltype (auto{v}), double *));
+ auto a1 = fn ();
+ static_assert (__is_same_as (decltype (auto(fn())), decltype (a1)));
+ static_assert (__is_same_as (decltype (auto{fn()}), decltype (a1)));
+ auto a2 = fnr ();
+ static_assert (__is_same_as (decltype (auto(fnr())), decltype (a2)));
+ static_assert (__is_same_as (decltype (auto{fnr()}), decltype (a2)));
+ +auto(1);
+ new auto(1);
+ +auto{1};
+ new auto{1};
+}
+
+template<typename T>
+void baz (T t, const T &tr, T &&trr)
+{
+ +auto(t);
+ +auto{t};
+ +auto(tr);
+ +auto{tr};
+ +auto(trr);
+ +auto{trr};
+ static_assert (__is_same_as (decltype (auto(t)), T));
+ static_assert (__is_same_as (decltype (auto{t}), T));
+ static_assert (__is_same_as (decltype (auto(tr)), T));
+ static_assert (__is_same_as (decltype (auto{tr}), T));
+ static_assert (__is_same_as (decltype (auto(trr)), T));
+ static_assert (__is_same_as (decltype (auto{trr}), T));
+}
+
+template<typename = decltype(auto(1))>
+void foo ()
+{
+}
+
+template<int = auto(1)>
+void bar ()
+{
+}
+
+void
+g()
+{
+ foo<>();
+ bar<>();
+ int i = 42;
+ baz (1, i, 42);
+}
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast3.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast3.C
new file mode 100644
index 00000000000..1204458c931
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast3.C
@@ -0,0 +1,21 @@
+// PR c++/103049
+// P0849R8 - auto(x)
+// { dg-do compile { target c++23 } }
+// Test invalid use.
+
+void
+f ()
+{
+ char x[] = "foo";
+ +decltype(auto){x}; // { dg-error "invalid use of .decltype\\(auto\\)." }
+ +decltype(auto)(x); // { dg-error "invalid use of .decltype\\(auto\\)." }
+
+ +auto(); // { dg-error "invalid use of .auto." }
+ new auto(); // { dg-error "requires exactly one element" }
+ +auto{}; // { dg-error "invalid use of .auto." }
+ new auto{}; // { dg-error "requires exactly one element" }
+ +auto(1, 2); // { dg-error "invalid use of .auto." }
+ new auto(1, 2); // { dg-error "requires exactly one element" }
+ +auto{1, 2}; // { dg-error "too many initializers" }
+ new auto{1, 2}; // { dg-error "requires exactly one element" }
+}
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast4.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast4.C
new file mode 100644
index 00000000000..0e26bf2bc66
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast4.C
@@ -0,0 +1,26 @@
+// PR c++/103049
+// P0849R8 - auto(x)
+// { dg-do compile { target c++23 } }
+
+class cmdline_parser
+{
+ public:
+ cmdline_parser(char const*);
+
+ auto add_option(char const*, char const*) & -> cmdline_parser &;
+ auto add_option(char const*, char const*) && -> cmdline_parser &&;
+
+ void parse(int, char**);
+};
+
+int main(int argc, char *argv[])
+{
+ auto cmdline = cmdline_parser("driver");
+
+ cmdline.add_option("-h", "show help messages")
+ .add_option("-v", "show version");
+
+ auto internal = auto(cmdline).add_option("--logging-level", "set logging level to 1-3")
+ .add_option("--dump-full", "do not minimize dump");
+ internal.parse(argc, argv);
+}
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast5.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast5.C
new file mode 100644
index 00000000000..b29901ffea4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast5.C
@@ -0,0 +1,39 @@
+// PR c++/103049
+// P0849R8 - auto(x)
+// { dg-do compile { target c++23 } }
+
+struct X {
+ X() = default;
+ X(const X&) = delete;
+};
+
+void
+g ()
+{
+ X x;
+ +X(x); // { dg-error "use of deleted function" }
+ +auto(x); // { dg-error "use of deleted function" }
+}
+
+class A;
+void f(A);
+
+class A {
+ int x;
+
+public:
+ A();
+
+ auto run() {
+ f(A(*this));
+ f(auto(*this));
+ }
+
+protected:
+ A(const A&);
+};
+
+void z () {
+ A a;
+ a.run ();
+}
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast6.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast6.C
new file mode 100644
index 00000000000..6b7858d9de5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast6.C
@@ -0,0 +1,14 @@
+// PR c++/103049
+// P0849R8 - auto(x)
+// { dg-do compile { target c++20 } }
+
+void f (int);
+
+void
+g ()
+{
+ auto a1 = auto(f); // { dg-error "only available with" "" { target c++20_only } }
+ auto a2 = auto{f}; // { dg-error "only available with" "" { target c++20_only } }
+ static_assert (__is_same_as (decltype (a1), void(*)(int)));
+ static_assert (__is_same_as (decltype (a2), void(*)(int)));
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C
index 290aaf83819..025bbf3bb93 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C
@@ -6,7 +6,8 @@ void foo1(T& t) {
typename T::template C<void> tcv = t;
typename T::template C<auto> u = tcv; // { dg-error "not permitted" "" { target c++20 } }
T::template C<auto>::f (tcv, u); // { dg-error "incomplete|not permitted" }
- (typename T::template D<auto> (t)); // { dg-error "invalid|not permitted" }
+ (typename T::template D<auto> (t)); // { dg-error "invalid|not permitted|unable" }
+// { dg-warning "only available" "" { target c++17_down } .-1 }
}
struct T1 {
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C
index d612327b9ae..80a388462eb 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C
@@ -10,7 +10,8 @@ void foo1(T& t) {
typename T::template C<void> tcv = t;
typename T::template C<auto> u = tcv; // { dg-error "not permitted" "" { target c++20 } }
T::template C<auto>::f (tcv, u); // { dg-error "incomplete|not permitted" }
- (typename T::template D<auto> (t)); // { dg-error "invalid|not permitted" }
+ (typename T::template D<auto> (t)); // { dg-error "invalid|not permitted|no class" }
+// { dg-warning "only available" "" { target c++17_down } .-1 }
}
struct T1 {
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