Re: C++ PATCH for c++/87781, detect invalid elaborated-type-specifier

[Jason Merrill <jason at redhat dot com>]

OK, thanks.
On Wed, Nov 14, 2018 at 3:32 PM Marek Polacek <polacek@redhat.com> wrote:
>
> On Wed, Nov 14, 2018 at 10:03:50AM -0500, Jason Merrill wrote:
> > On Wed, Nov 14, 2018 at 9:55 AM Marek Polacek <polacek@redhat.com> wrote:
> > >
> > > In elaborated-type-specifier, the typename keyword can only follow a
> > > nested-name-specifier:
> > >
> > >   class-key nested-name-specifier template[opt] simple-template-id
> > >
> > > but we weren't detecting it.
> > >
> > > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> > >
> > > 2018-11-14  Marek Polacek  <polacek@redhat.com>
> > >
> > >         PR c++/87781 - detect invalid elaborated-type-specifier.
> > >         * parser.c (cp_parser_elaborated_type_specifier): Ensure that
> > >         typename follows a nested-name-specifier.
> > >
> > >         * g++.dg/parse/elab3.C: New test.
> > >
> > > diff --git gcc/cp/parser.c gcc/cp/parser.c
> > > index e9e49b15702..0ab44ab93e3 100644
> > > --- gcc/cp/parser.c
> > > +++ gcc/cp/parser.c
> > > @@ -17986,6 +17986,10 @@ cp_parser_elaborated_type_specifier (cp_parser* parser,
> > >          template-id or not.  */
> > >        if (!template_p)
> > >         cp_parser_parse_tentatively (parser);
> > > +      /* The `template' keyword must follow a nested-name-specifier.  */
> > > +      else if (!nested_name_specifier)
> > > +       return error_mark_node;
> >
> > Don't we want a diagnostic here?
>
> We'd get "invalid declarator" even without a diagnostic there but I guess it'd
> be nicer so say what the actual problem is.  Unsure which diagnostic to go with,
> this patch uses cp_parser_error though.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-11-14  Marek Polacek  <polacek@redhat.com>
>
>         PR c++/87781 - detect invalid elaborated-type-specifier.
>         * parser.c (cp_parser_elaborated_type_specifier): Ensure that
>         typename follows a nested-name-specifier.
>
>         * g++.dg/parse/elab3.C: New test.
>         * g++.dg/template/crash115.C: Adjust dg-error.
>
> diff --git gcc/cp/parser.c gcc/cp/parser.c
> index e9e49b15702..bfcf42b0f39 100644
> --- gcc/cp/parser.c
> +++ gcc/cp/parser.c
> @@ -17986,6 +17986,14 @@ cp_parser_elaborated_type_specifier (cp_parser* parser,
>          template-id or not.  */
>        if (!template_p)
>         cp_parser_parse_tentatively (parser);
> +      /* The `template' keyword must follow a nested-name-specifier.  */
> +      else if (!nested_name_specifier)
> +       {
> +         cp_parser_error (parser, "%<template%> must follow a nested-"
> +                          "name-specifier");
> +         return error_mark_node;
> +       }
> +
>        /* Parse the template-id.  */
>        token = cp_lexer_peek_token (parser->lexer);
>        decl = cp_parser_template_id (parser, template_p,
> diff --git gcc/testsuite/g++.dg/parse/elab3.C gcc/testsuite/g++.dg/parse/elab3.C
> new file mode 100644
> index 00000000000..61338fb7ac4
> --- /dev/null
> +++ gcc/testsuite/g++.dg/parse/elab3.C
> @@ -0,0 +1,6 @@
> +// PR c++/87781
> +// { dg-do compile }
> +// { dg-options "" }
> +
> +template<class> class A;
> +class template A<int> *p; // { dg-error ".template. must follow|invalid" }
> diff --git gcc/testsuite/g++.dg/template/crash115.C gcc/testsuite/g++.dg/template/crash115.C
> index 5c9f525cd64..80f8683a136 100644
> --- gcc/testsuite/g++.dg/template/crash115.C
> +++ gcc/testsuite/g++.dg/template/crash115.C
> @@ -1,3 +1,3 @@
>  // PR c++/56534
>
> -template < struct template rebind < > // { dg-error "expected" }
> +template < struct template rebind < > // { dg-error "expected|must follow" }