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c++: Disallow this specifier except for parameter declarations [PR113788]

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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.

2024-02-06  Jakub Jelinek  <jakub@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.
This commit is contained in:
Jakub Jelinek 2024-02-06 22:34:55 +01:00
parent f2a060820c
commit 40485378ad
2 changed files with 25 additions and 3 deletions
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8
gcc/cp/parser.cc
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@ -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* 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_parser *parser,
/* 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);

20
gcc/testsuite/g++.dg/parse/pr113788.C Normal file
View file

@ -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" }