c++: __extension__ and -Wconditionally-supported

When we're explicitly choosing GCC extensions, we similarly shouldn't
complain about optional features that GCC provides.  This particular pattern
of cast between function and object pointer is used by gthr-posix.h on some
targets, including linux-gnu before glibc 2.34.

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_unary_expression) [RID_EXTENSION]: Also
	suppress -Wconditionally-supported.

gcc/testsuite/ChangeLog:

	* g++.dg/warn/Wconditionally-supported-1.C: Add __extension__ cases.

diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 3c8c75575b04fc2cc0142cb6a3ae1b3917d719d9..4dd9474cf609e22d076e4f7a2af0a74f10dc5791 100644 (file)
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -9150,9 +9150,15 @@ cp_parser_unary_expression (cp_parser *parser, cp_id_kind * pidk,
 
            /* Save away the PEDANTIC flag.  */
            cp_parser_extension_opt (parser, &saved_pedantic);
+           /* Also suppress -Wconditionally-supported.  */
+           diagnostic_push_diagnostics (global_dc, input_location);
+           diagnostic_classify_diagnostic
+             (global_dc, OPT_Wconditionally_supported,
+              DK_IGNORED, input_location);
            /* Parse the cast-expression.  */
            expr = cp_parser_simple_cast_expression (parser);
            /* Restore the PEDANTIC flag.  */
+           diagnostic_pop_diagnostics (global_dc, input_location);
            pedantic = saved_pedantic;
 
            return expr;

diff --git a/gcc/testsuite/g++.dg/warn/Wconditionally-supported-1.C b/gcc/testsuite/g++.dg/warn/Wconditionally-supported-1.C
index 3c32edba8cecdc18771d29158e47ce2ccb159e18..192d709fd79909883be63a415d40c0e04ecc6cac 100644 (file)
--- a/gcc/testsuite/g++.dg/warn/Wconditionally-supported-1.C
+++ b/gcc/testsuite/g++.dg/warn/Wconditionally-supported-1.C
@@ -22,4 +22,10 @@ void foo ()
 
   pf = reinterpret_cast <PF>(po); // { dg-warning "8:casting between pointer-to-function and pointer-to-object is conditionally-supported" }
   po = reinterpret_cast <PO>(pf); // { dg-warning "8:casting between pointer-to-function and pointer-to-object is conditionally-supported" }
+
+  pf = __extension__ reinterpret_cast <PF>(pv);
+  pv = __extension__ reinterpret_cast <PV>(pf);
+
+  pf = __extension__ reinterpret_cast <PF>(po);
+  po = __extension__ reinterpret_cast <PO>(pf);
 }