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Re: [C++ PATCH] Disallow type specifiers among lambda-declarator decl-specifier-seq (PR c++/86550)


On Wed, Jul 18, 2018 at 11:34:30AM +1000, Jason Merrill wrote:
> On Wed, Jul 18, 2018 at 4:57 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> > The standard says:
> > "In the decl-specifier-seq of the lambda-declarator, each decl-specifier shall
> > either be mutable or constexpr."
> > and the C++ FE has CP_PARSER_FLAGS_ONLY_MUTABLE_OR_CONSTEXPR flag for that.
> > But as implemented, it is actually
> > CP_PARSER_FLAGS_ONLY_TYPE_OR_MUTABLE_OR_CONSTEXPR
> > as it allows mutable, constexpr and type specifiers.
> >
> > Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> > trunk?
> >
> > 2018-07-17  Jakub Jelinek  <jakub@redhat.com>
> >
> >         PR c++/86550
> >         * parser.c (cp_parser_decl_specifier_seq): Don't parse a type specifier
> >         if CP_PARSER_FLAGS_ONLY_MUTABLE_OR_CONSTEXPR.
> 
> I think the diagnostic would be better if we parse the type-specifier
> and then give an error about it being invalid in this context, rather
> than not parse it and therefore give a syntax error; the constraint is
> semantic rather than syntactic.

So like this?
It will diagnose each bool and int separately, but that is similar to how it
will diagnose
[] () static extern thread_local inline virtual virtual explicit {}
too.

2018-07-18  Jakub Jelinek  <jakub@redhat.com>

	PR c++/86550
	* parser.c (cp_parser_decl_specifier_seq): Diagnose invalid type
	specifier if CP_PARSER_FLAGS_ONLY_MUTABLE_OR_CONSTEXPR.

	* g++.dg/cpp0x/lambda/lambda-86550.C: New test.

--- gcc/cp/parser.c.jj	2018-07-17 20:08:07.630224343 +0200
+++ gcc/cp/parser.c	2018-07-18 10:09:10.655030931 +0200
@@ -13797,6 +13797,9 @@ cp_parser_decl_specifier_seq (cp_parser*
 	      found_decl_spec = true;
 	      if (!is_cv_qualifier)
 		decl_specs->any_type_specifiers_p = true;
+
+	      if ((flags & CP_PARSER_FLAGS_ONLY_MUTABLE_OR_CONSTEXPR) != 0)
+		error_at (token->location, "type-specifier invalid in lambda");
 	    }
 	}
 
--- gcc/testsuite/g++.dg/cpp0x/lambda/lambda-86550.C.jj	2018-07-18 10:05:02.894767883 +0200
+++ gcc/testsuite/g++.dg/cpp0x/lambda/lambda-86550.C	2018-07-18 10:13:41.373318350 +0200
@@ -0,0 +1,9 @@
+// PR c++/86550
+// { dg-do compile { target c++11 } }
+
+void
+foo ()
+{
+  auto a = []() bool {};			// { dg-error "type-specifier invalid in lambda" }
+  auto b = []() bool bool bool bool int {};	// { dg-error "type-specifier invalid in lambda" }
+}


	Jakub


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