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Objective-C++ : Allow prefix attrs on linkage specs.

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For Objective-C++, this combines prefix attributes from before and
after top level linkage specs.  The "reference implementation" for
Objective-C++ allows this, and system headers depend on it.

e.g.

__attribute__((__deprecated__))
extern "C" __attribute__((__visibility__("default")))
@interface MyClass
...
@end

Would consider the list of prefix attributes to the interface for
MyClass to include both the visibility and deprecated ones.

When we are compiling regular C++, this emits a warning and discards
any prefix attributes before a linkage spec.

gcc/cp/ChangeLog:

	* parser.c (cp_parser_declaration): Unless we are compiling for
	Ojective-C++, warn about and discard any attributes that prefix
	a linkage specification.
This commit is contained in:
Iain Sandoe 2020-10-26 22:12:22 +00:00
parent b1c9b3c340
commit 9227f81db7
1 changed files with 57 additions and 14 deletions
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71
gcc/cp/parser.c
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@ -2187,7 +2187,7 @@ static void cp_parser_already_scoped_statement
static void cp_parser_declaration_seq_opt
(cp_parser *);
static void cp_parser_declaration
(cp_parser *);
(cp_parser *, tree);
static void cp_parser_toplevel_declaration
(cp_parser *);
static void cp_parser_block_declaration
@ -2238,7 +2238,7 @@ static tree cp_parser_alias_declaration
static void cp_parser_asm_definition
(cp_parser *);
static void cp_parser_linkage_specification
(cp_parser *);
(cp_parser *, tree);
static void cp_parser_static_assert
(cp_parser *, bool);
static tree cp_parser_decltype
@ -13496,7 +13496,7 @@ cp_parser_declaration_seq_opt (cp_parser* parser)
__extension__ declaration */
static void
cp_parser_declaration (cp_parser* parser)
cp_parser_declaration (cp_parser* parser, tree prefix_attrs)
{
int saved_pedantic;
@ -13504,7 +13504,7 @@ cp_parser_declaration (cp_parser* parser)
if (cp_parser_extension_opt (parser, &saved_pedantic))
{
/* Parse the qualified declaration. */
cp_parser_declaration (parser);
cp_parser_declaration (parser, prefix_attrs);
/* Restore the PEDANTIC flag. */
pedantic = saved_pedantic;
@ -13521,11 +13521,50 @@ cp_parser_declaration (cp_parser* parser)
tree attributes = NULL_TREE;
/* Conditionally, allow attributes to precede a linkage specification. */
if (token1->keyword == RID_ATTRIBUTE)
{
cp_lexer_save_tokens (parser->lexer);
attributes = cp_parser_attributes_opt (parser);
gcc_checking_assert (attributes);
cp_token *t1 = cp_lexer_peek_token (parser->lexer);
cp_token *t2 = (t1->type == CPP_EOF
? t1 : cp_lexer_peek_nth_token (parser->lexer, 2));
if (t1->keyword == RID_EXTERN
&& cp_parser_is_pure_string_literal (t2))
{
cp_lexer_commit_tokens (parser->lexer);
/* We might have already been here. */
if (!c_dialect_objc ())
{
warning_at (token1->location, OPT_Wattributes, "attributes are"
" only permitted in this position for Objective-C++,"
" ignored");
attributes = NULL_TREE;
}
token1 = t1;
token2 = t2;
}
else
{
cp_lexer_rollback_tokens (parser->lexer);
attributes = NULL_TREE;
}
}
/* If we already had some attributes, and we've added more, then prepend.
Otherwise attributes just contains any that we just read. */
if (prefix_attrs)
{
if (attributes)
TREE_CHAIN (prefix_attrs) = attributes;
attributes = prefix_attrs;
}
/* If the next token is `extern' and the following token is a string
literal, then we have a linkage specification. */
if (token1->keyword == RID_EXTERN
&& cp_parser_is_pure_string_literal (token2))
cp_parser_linkage_specification (parser);
cp_parser_linkage_specification (parser, attributes);
/* If the next token is `template', then we have either a template
declaration, an explicit instantiation, or an explicit
specialization. */
@ -13575,7 +13614,7 @@ cp_parser_declaration (cp_parser* parser)
cp_parser_namespace_definition (parser);
/* Objective-C++ declaration/definition. */
else if (c_dialect_objc () && OBJC_IS_AT_KEYWORD (token1->keyword))
cp_parser_objc_declaration (parser, NULL_TREE);
cp_parser_objc_declaration (parser, attributes);
else if (c_dialect_objc ()
&& token1->keyword == RID_ATTRIBUTE
&& cp_parser_objc_valid_prefix_attributes (parser, &attributes))
@ -13617,7 +13656,7 @@ cp_parser_toplevel_declaration (cp_parser* parser)
}
else
/* Parse the declaration itself. */
cp_parser_declaration (parser);
cp_parser_declaration (parser, NULL_TREE);
}
/* Parse a block-declaration.
@ -14726,7 +14765,7 @@ cp_parser_function_specifier_opt (cp_parser* parser,
extern string-literal declaration */
static void
cp_parser_linkage_specification (cp_parser* parser)
cp_parser_linkage_specification (cp_parser* parser, tree prefix_attr)
{
tree linkage;
@ -14791,7 +14830,7 @@ cp_parser_linkage_specification (cp_parser* parser)
saved_in_unbraced_linkage_specification_p
= parser->in_unbraced_linkage_specification_p;
parser->in_unbraced_linkage_specification_p = true;
cp_parser_declaration (parser);
cp_parser_declaration (parser, prefix_attr);
parser->in_unbraced_linkage_specification_p
= saved_in_unbraced_linkage_specification_p;
}
@ -33099,7 +33138,7 @@ cp_parser_objc_interstitial_code (cp_parser* parser)
if (token->keyword == RID_EXTERN
&& cp_parser_is_pure_string_literal
(cp_lexer_peek_nth_token (parser->lexer, 2)))
cp_parser_linkage_specification (parser);
cp_parser_linkage_specification (parser, NULL_TREE);
/* Handle #pragma, if any. */
else if (token->type == CPP_PRAGMA)
cp_parser_pragma (parser, pragma_objc_icode, NULL);
@ -33864,11 +33903,15 @@ static bool
cp_parser_objc_valid_prefix_attributes (cp_parser* parser, tree *attrib)
{
cp_lexer_save_tokens (parser->lexer);
*attrib = cp_parser_attributes_opt (parser);
gcc_assert (*attrib);
tree addon = cp_parser_attributes_opt (parser);
gcc_checking_assert (addon);
if (OBJC_IS_AT_KEYWORD (cp_lexer_peek_token (parser->lexer)->keyword))
{
cp_lexer_commit_tokens (parser->lexer);
if (*attrib)
TREE_CHAIN (*attrib) = addon;
else
*attrib = addon;
return true;
}
cp_lexer_rollback_tokens (parser->lexer);
@ -41892,7 +41935,7 @@ cp_parser_omp_declare_simd (cp_parser *parser, cp_token *pragma_tok,
switch (context)
{
case pragma_external:
cp_parser_declaration (parser);
cp_parser_declaration (parser, NULL_TREE);
break;
case pragma_member:
cp_parser_member_declaration (parser);
@ -43449,7 +43492,7 @@ cp_parser_oacc_routine (cp_parser *parser, cp_token *pragma_tok,
}
/* We only have to consider the pragma_external case here. */
cp_parser_declaration (parser);
cp_parser_declaration (parser, NULL_TREE);
if (parser->oacc_routine
&& !parser->oacc_routine->fndecl_seen)
cp_ensure_no_oacc_routine (parser);