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c++: Don't emit deprecated warnings or unavailable errors on lambda declarations

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On the following testcase, we emit deprecated warnings or unavailable errors
even on merge declarations of those lambdas (the dg-bogus directives), while
IMHO we should emit them only when something actually calls those lambdas.

The following patch temporarily disables that diagnostics during
maybe_add_lambda_conv_op.

PR2173R1 also says that ambiguity between attribute-specifier-seq at the
end of requires-clause and attribute-specifier-seq from lambda-expression
should be resolved to attribute-specifier-seq for the latter.  Do we need
to do anything about that?  I mean, can a valid requires-clause end with
an attribute-specifier-seq?  Say operator int [[]] is valid primary
expression, but requires operator int [[]] isn't valid, nor is
requires operator int, no?

2022-05-04  Jakub Jelinek  <jakub@redhat.com>

	* lambda.cc: Include decl.h.
	(maybe_add_lambda_conv_op): Temporarily override deprecated_state to
	UNAVAILABLE_DEPRECATED_SUPPRESS.

	* g++.dg/cpp23/lambda-attr1.C: New test.
	* g++.dg/cpp23/lambda-attr2.C: New test.

(cherry picked from commit 1c8e9bed9b)
This commit is contained in:
Jakub Jelinek 2022-05-04 10:07:36 +02:00
parent f2c2ebb9ee
commit 8b26d0e28b
3 changed files with 65 additions and 3 deletions
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12
gcc/cp/lambda.cc
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@ -31,6 +31,7 @@ along with GCC; see the file COPYING3. If not see
#include "toplev.h"
#include "gimplify.h"
#include "target.h"
#include "decl.h"
/* Constructor for a lambda expression. */
@ -1193,9 +1194,14 @@ maybe_add_lambda_conv_op (tree type)
}
}
else
call = build_call_a (callop,
direct_argvec->length (),
direct_argvec->address ());
{
/* Don't warn on deprecated or unavailable lambda declarations, unless
the lambda is actually called. */
auto du = make_temp_override (deprecated_state,
UNAVAILABLE_DEPRECATED_SUPPRESS);
call = build_call_a (callop, direct_argvec->length (),
direct_argvec->address ());
}
CALL_FROM_THUNK_P (call) = 1;
SET_EXPR_LOCATION (call, UNKNOWN_LOCATION);

37
gcc/testsuite/g++.dg/cpp23/lambda-attr1.C Normal file
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@ -0,0 +1,37 @@
// P2173R1 - Attributes on Lambda-Expressions
// { dg-do compile { target c++11 } }
void
foo (bool x, bool y)
{
auto a = [][[noreturn]] () {}; // { dg-warning "'noreturn' function does return" }
if (x)
a ();
auto b = [][[noreturn]] {}; // { dg-warning "'noreturn' function does return" }
if (y)
b ();
auto c = [] [[ deprecated ]] () {}; // { dg-bogus "is deprecated" }
c (); // { dg-warning "'foo\\\(bool, bool\\\)::<lambda\\\(\\\)>' is deprecated" }
auto d = [][[deprecated]] {}; // { dg-bogus "is deprecated" }
d (); // { dg-warning "'foo\\\(bool, bool\\\)::<lambda\\\(\\\)>' is deprecated" }
#if __cpp_generic_lambdas >= 201304
auto e = [] [[deprecated]] (auto x) {}; // { dg-bogus "is deprecated" }
e (0.0); // { dg-warning "'foo\\\(bool, bool\\\)::<lambda\\\(auto:1\\\)>\[^\n\r]*' is deprecated" "" { target c++14 } }
#endif
#if __cpp_generic_lambdas >= 201707
auto f = [] <typename T> [[deprecated]] (T) {}; // { dg-bogus "is deprecated" }
f (1); // { dg-warning "'foo\\\(bool, bool\\\)::<lambda\\\(T\\\)>\[^\n\r]*' is deprecated" "" { target c++20 } }
#endif
auto g = [][[nodiscard]](int) { return 1; };
g (1); // { dg-warning "ignoring return value of 'foo\\\(bool, bool\\\)::<lambda\\\(int\\\)>', declared with attribute 'nodiscard'" }
auto h = [] [[nodiscard]] { return 0; };
h (); // { dg-warning "ignoring return value of 'foo\\\(bool, bool\\\)::<lambda\\\(\\\)>', declared with attribute 'nodiscard'" }
auto i = [] [[ gnu::unavailable ]] () {};
auto j = [][[gnu::unavailable]] {};
#if __cpp_generic_lambdas >= 201304
auto k = [] [[gnu::unavailable]] (auto x) {}; // { dg-bogus "is unavailable" }
#endif
#if __cpp_generic_lambdas >= 201707
auto l = [] <typename T> [[gnu::unavailable]] (T) {}; // { dg-bogus "is unavailable" }
#endif
}

19
gcc/testsuite/g++.dg/cpp23/lambda-attr2.C Normal file
View File

@ -0,0 +1,19 @@
// P2173R1 - Attributes on Lambda-Expressions
// { dg-do compile { target c++11 } }
void
foo (bool x, bool y)
{
auto i = [] [[ gnu::unavailable ]] () {};
i (); // { dg-error "'foo\\\(bool, bool\\\)::<lambda\\\(\\\)>' is unavailable" }
auto j = [][[gnu::unavailable]] {};
j (); // { dg-error "'foo\\\(bool, bool\\\)::<lambda\\\(\\\)>' is unavailable" }
#if __cpp_generic_lambdas >= 201304
auto k = [] [[gnu::unavailable]] (auto x) {}; // { dg-bogus "is unavailable" }
k (0.0); // { dg-error "'foo\\\(bool, bool\\\)::<lambda\\\(auto:1\\\)>\[^\n\r]*' is unavailable" "" { target c++14 } }
#endif
#if __cpp_generic_lambdas >= 201707
auto l = [] <typename T> [[gnu::unavailable]] (T) {}; // { dg-bogus "is unavailable" }
l (1); // { dg-error "'foo\\\(bool, bool\\\)::<lambda\\\(T\\\)>\[^\n\r]*' is unavailable" "" { target c++20 } }
#endif
}