On Tue, Feb 06, 2024 at 09:37:44PM +0100, Jakub Jelinek wrote:
> Hi!
>
> The deducing this patchset added parsing of this specifier to
> cp_parser_decl_specifier_seq unconditionally, but in the C++ grammar
> this[opt] only appears in the parameter-declaration non-terminal, so
> rather than checking in all the callers of cp_parser_decl_specifier_seq
> except for cp_parser_parameter_declaration that this specifier didn't
> appear I think it is far easier and closer to what the standard says
> to only parse this specifier when called from
> cp_parser_parameter_declaration.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
FWIW, the patch looks good to me.
> 2024-02-06 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/113788
> * parser.cc (CP_PARSER_FLAGS_PARAMETER): New enumerator.
> (cp_parser_decl_specifier_seq): Parse RID_THIS only if
> CP_PARSER_FLAGS_PARAMETER is set in flags.
> (cp_parser_parameter_declaration): Or in CP_PARSER_FLAGS_PARAMETER
> when calling cp_parser_decl_specifier_seq.
>
> * g++.dg/parse/pr113788.C: New test.
>
> --- gcc/cp/parser.cc.jj 2024-01-17 10:34:45.337660930 +0100
> +++ gcc/cp/parser.cc 2024-02-06 18:31:35.587193903 +0100
> @@ -2088,7 +2088,9 @@ enum
> /* When parsing of the noexcept-specifier should be delayed. */
> CP_PARSER_FLAGS_DELAY_NOEXCEPT = 0x40,
> /* When parsing a consteval declarator. */
> - CP_PARSER_FLAGS_CONSTEVAL = 0x80
> + CP_PARSER_FLAGS_CONSTEVAL = 0x80,
> + /* When parsing a parameter declaration. */
> + CP_PARSER_FLAGS_PARAMETER = 0x100
> };
>
> /* This type is used for parameters and variables which hold
> @@ -16342,7 +16344,7 @@ cp_parser_decl_specifier_seq (cp_parser*
> /* Special case for "this" specifier, indicating a parm is an xobj
> parm.
> The "this" specifier must be the first specifier in the declaration,
> after any attributes. */
> - if (token->keyword == RID_THIS)
> + if (token->keyword == RID_THIS && (flags & CP_PARSER_FLAGS_PARAMETER))
> {
> cp_lexer_consume_token (parser->lexer);
> if (token != first_specifier)
> @@ -25607,7 +25609,7 @@ cp_parser_parameter_declaration (cp_pars
> /* Parse the declaration-specifiers. */
> cp_token *decl_spec_token_start = cp_lexer_peek_token (parser->lexer);
> cp_parser_decl_specifier_seq (parser,
> - flags,
> + flags | CP_PARSER_FLAGS_PARAMETER,
> &decl_specifiers,
> &declares_class_or_enum);
>
> --- gcc/testsuite/g++.dg/parse/pr113788.C.jj 2024-02-06 18:40:29.553791028
> +0100
> +++ gcc/testsuite/g++.dg/parse/pr113788.C 2024-02-06 18:41:23.326045703
> +0100
> @@ -0,0 +1,20 @@
> +// PR c++/113788
> +// { dg-do compile { target c++11 } }
> +
> +struct S { int a, b; };
> +struct U {
> + void foo () { this int g = 1; } // { dg-error "expected ';' before
> 'int'" }
> +};
> +this auto h = 1; // { dg-error "expected unqualified-id
> before 'this'" }
> +
> +int
> +main ()
> +{
> + S s = { 1, 2 };
> + short t[3] = { 3, 4, 5 };
> + this auto &[a, b] = s; // { dg-error "invalid use of 'this' in
> non-member function" }
> + this auto &[c, d, e] = t; // { dg-error "invalid use of 'this' in
> non-member function" }
> + this int f = 1; // { dg-error "invalid use of 'this' in
> non-member function" }
> + for (this auto &i : t) // { dg-error "invalid use of 'this' in
> non-member function" }
> + ; // { dg-error "expected" }
> +} // { dg-error "expected" }
>
> Jakub
>
Marek
