From 6afb8a68a9113897ccf39e40983e042ed90d7aed Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Thu, 16 Dec 2021 16:29:41 -0500 Subject: attribs: Fix wrong error with -Wno-attribute=A::b [PR103649] My patch to implement -Wno-attribute=A::b caused a bogus error when parsing [[foo::bar(1, 2)]]; when -Wno-attributes=foo::bar was specified on the command line, because when we create a fake foo::bar attribute and insert it into our attribute table, it is created with max_length == 0 which doesn't allow any args. That is wrong -- we know nothing about the attribute, so we shouldn't require any specific number of arguments. And since unknown attributes can be rather complex (see for example omp::{directive,sequence}), we must skip parsing their arguments. To that end, I'm using max_length with value -2. Also let's not warn about things like [[vendor::assume(true)]]; because they may have some meaning (this is reminiscent of C++ Portable Assumptions). PR c/103649 gcc/ChangeLog: * attribs.c (handle_ignored_attributes_option): Create the fake attribute with max_length == -2. (attribute_ignored_p): New overloads. * attribs.h (attribute_ignored_p): Declare them. * tree-core.h (struct attribute_spec): Document that max_length can be -2. gcc/c/ChangeLog: * c-decl.c (c_warn_unused_attributes): Don't warn for attribute_ignored_p. * c-parser.c (c_parser_std_attribute): Skip parsing of the attribute arguments when the attribute is ignored. gcc/cp/ChangeLog: * parser.c (cp_parser_declaration): Don't warn for attribute_ignored_p. (cp_parser_std_attribute): Skip parsing of the attribute arguments when the attribute is ignored. gcc/testsuite/ChangeLog: * c-c++-common/Wno-attributes-6.c: New test. --- gcc/cp/parser.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'gcc/cp/parser.c') diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index 44eed7e..33fb40a 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -14776,7 +14776,7 @@ cp_parser_declaration (cp_parser* parser, tree prefix_attrs) } } - if (std_attrs != NULL_TREE) + if (std_attrs != NULL_TREE && !attribute_ignored_p (std_attrs)) warning_at (make_location (attrs_loc, attrs_loc, parser->lexer), OPT_Wattributes, "attribute ignored"); if (cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON)) @@ -28979,7 +28979,9 @@ cp_parser_std_attribute (cp_parser *parser, tree attr_ns) /* A GNU attribute that takes an identifier in parameter. */ attr_flag = id_attr; - if (as == NULL) + /* If this is a fake attribute created to handle -Wno-attributes, + we must skip parsing the arguments. */ + if (as == NULL || attribute_ignored_p (as)) { if ((flag_openmp || flag_openmp_simd) && attr_ns == omp_identifier) { -- cgit v1.1