Re: [PATCH] c++: Fox template-introduction tentative parsing in class bodies clear colon_corrects_to_scope_p [PR105061]

[Jason Merrill <jason@redhat.com>]

On 3/29/22 04:05, Jakub Jelinek wrote:
> Hi!
> 
> The concepts support (in particular template introductions from concepts TS)
> broke the following testcase, valid unnamed bitfields with dependent
> types (or even just typedefs) were diagnosed as typos (: instead of correct
> ::) in template introduction during their tentative parsing.
> The following patch fixes that by not doing this : to :: correction when
> member_p is true.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk and
> release branches (so far also bootstrapped/regtested on the above targets
> on 11 branch)?

OK.

> 2022-03-29  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR c++/105061
> 	* parser.cc (cp_parser_template_introduction): If member_p, temporarily
> 	clear parser->colon_corrects_to_scope_p around tentative parsing of
> 	nested name specifier.
> 
> 	* g++.dg/concepts/pr105061.C: New test.
> 
> --- gcc/cp/parser.cc.jj	2022-03-26 08:11:50.030217910 +0100
> +++ gcc/cp/parser.cc	2022-03-28 17:30:41.488053848 +0200
> @@ -31417,9 +31417,15 @@ cp_parser_template_introduction (cp_pars
>     tree saved_scope = parser->scope;
>     tree saved_object_scope = parser->object_scope;
>     tree saved_qualifying_scope = parser->qualifying_scope;
> +  bool saved_colon_corrects_to_scope_p = parser->colon_corrects_to_scope_p;
>   
>     cp_token *start_token = cp_lexer_peek_token (parser->lexer);
>   
> +  /* In classes don't parse valid unnamed bitfields as invalid
> +     template introductions.  */
> +  if (member_p)
> +    parser->colon_corrects_to_scope_p = false;
> +
>     /* Look for the optional `::' operator.  */
>     cp_parser_global_scope_opt (parser,
>   			      /*current_scope_valid_p=*/false);
> @@ -31440,6 +31446,7 @@ cp_parser_template_introduction (cp_pars
>     parser->scope = saved_scope;
>     parser->object_scope = saved_object_scope;
>     parser->qualifying_scope = saved_qualifying_scope;
> +  parser->colon_corrects_to_scope_p = saved_colon_corrects_to_scope_p;
>   
>     if (concept_name == error_mark_node
>         || (seen_error () && !concept_definition_p (tmpl_decl)))
> --- gcc/testsuite/g++.dg/concepts/pr105061.C.jj	2022-03-28 17:34:02.051207207 +0200
> +++ gcc/testsuite/g++.dg/concepts/pr105061.C	2022-03-28 17:33:14.502882074 +0200
> @@ -0,0 +1,13 @@
> +// PR c++/105061
> +
> +template <typename T, int U, int V>
> +struct A { T : V, u : U; };
> +template <int U, int V>
> +struct B { unsigned : V, u : U; };
> +typedef unsigned uns;
> +template <int U, int V>
> +struct C { uns : V, u : U; };
> +
> +A<unsigned int, 4, 5> a = { 13 };
> +B<5, 6> b = { 26 };
> +C<8, 9> c = { 42 };
> 
> 	Jakub
>