On 5/2/22 07:11, Jakub Jelinek wrote:
Hi!
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.
Ok for trunk if it passes bootstrap/regtest?
OK.
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?
I agree, I don't understand what those examples in the paper were
supposed to mean.
2022-05-02 Jakub Jelinek <ja...@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.
--- gcc/cp/lambda.cc.jj 2022-05-02 07:10:02.360150857 +0200
+++ gcc/cp/lambda.cc 2022-05-02 12:38:24.906950325 +0200
@@ -31,6 +31,7 @@ along with GCC; see the file COPYING3.
#include "toplev.h"
#include "gimplify.h"
#include "target.h"
+#include "decl.h"
/* Constructor for a lambda expression. */
@@ -1192,9 +1193,14 @@ 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);
--- gcc/testsuite/g++.dg/cpp23/lambda-attr1.C.jj 2022-05-02
12:25:32.604570154 +0200
+++ gcc/testsuite/g++.dg/cpp23/lambda-attr1.C 2022-05-02 12:44:21.509041161
+0200
@@ -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
+}
--- gcc/testsuite/g++.dg/cpp23/lambda-attr2.C.jj 2022-05-02
12:44:30.099922893 +0200
+++ gcc/testsuite/g++.dg/cpp23/lambda-attr2.C 2022-05-02 12:48:29.234630831
+0200
@@ -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
+}
Jakub
