Re: C++ PATCH to fix a part of c++/70513 (ICE-on-invalid with enums)

[Marek Polacek <polacek at redhat dot com>]

Ping.

On Fri, Apr 08, 2016 at 01:51:02PM +0200, Marek Polacek wrote:
> This is my attempt to fix at least a part of this PR.  I haven't been able to
> come up with a fix that fixes the other part involving templates.
> 
> We were ICEing on code such as
> 
> struct S
> {
>   enum E : int;
>   enum S::E : int { foo } e;
> };
> 
> Clang rejects this with "extra qualification" error.  When I modified the test
> to use structs rather than enums...
> 
> struct T
> {
>   struct U;
>   struct T::U {};
> };
> 
> ...I found out that we reject this with "extra qualification not allowed".  So
> I think the enum case is missing a similar check that this patch adds.
> 
> By the template part of this PR I mean that we ICE on
> 
> template <typename T>
> class D
> {
>   enum D::A { foo } c;
> };
> 
> where clang++ says
> error: template specialization or definition requires a template parameter list
>        corresponding to the nested type 'D<T>'
> which I guess means that a valid code would have "<T>" after "D".  I thought
> num_template_headers_for_class and cp_parser_check_template_parameters would
> do the job here, but apparently something else needs to be used for this case.
> But I'm at my wits' end here.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> 2016-04-08  Marek Polacek  <polacek@redhat.com>
> 
> 	PR c++/70513
> 	* parser.c (cp_parser_enum_specifier): Check for extra qualification.
> 
> 	* g++.dg/cpp0x/forw_enum12.C: New test.
> 
> diff --git gcc/cp/parser.c gcc/cp/parser.c
> index 28e01af..dc0d1c8 100644
> --- gcc/cp/parser.c
> +++ gcc/cp/parser.c
> @@ -17231,6 +17231,15 @@ cp_parser_enum_specifier (cp_parser* parser)
>  			  type, prev_scope, nested_name_specifier);
>  	      type = error_mark_node;
>  	    }
> +	  /* If that scope is the scope where the declaration is being placed
> +	     the program is invalid.  */
> +	  else if (nested_name_specifier == prev_scope)
> +	    {
> +	      permerror (type_start_token->location,
> +			 "extra qualification not allowed");
> +	      type = error_mark_node;
> +	      nested_name_specifier = NULL_TREE;
> +	    }
>  	}
>  
>        if (scoped_enum_p)
> diff --git gcc/testsuite/g++.dg/cpp0x/forw_enum12.C gcc/testsuite/g++.dg/cpp0x/forw_enum12.C
> index e69de29..906ba68 100644
> --- gcc/testsuite/g++.dg/cpp0x/forw_enum12.C
> +++ gcc/testsuite/g++.dg/cpp0x/forw_enum12.C
> @@ -0,0 +1,29 @@
> +// PR c++/70513
> +// { dg-do compile { target c++11 } }
> +
> +struct S1
> +{
> +  enum E : int;
> +  enum S1::E : int { X } e; // { dg-error "extra qualification not allowed" }
> +};
> +
> +struct S2
> +{
> +  enum class E : int;
> +  enum class S2::E : int { X } e; // { dg-error "extra qualification not allowed" }
> +};
> +
> +struct S3
> +{
> +  enum struct E : int;
> +  enum struct S3::E : int { X } e; // { dg-error "extra qualification not allowed" }
> +};
> +
> +struct S4
> +{
> +  struct S5
> +  {
> +    enum E : char;
> +    enum S4::S5::E : char { X } e; // { dg-error "extra qualification not allowed" }
> +  };
> +};
> 
> 	Marek

	Marek