diff options
Diffstat (limited to 'gcc/c/c-parser.c')
| -rw-r--r-- | gcc/c/c-parser.c | 54 |
1 files changed, 52 insertions, 2 deletions
diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c index 5b290bf..e48760d 100644 --- a/gcc/c/c-parser.c +++ b/gcc/c/c-parser.c @@ -4873,6 +4873,9 @@ c_parser_std_attribute (c_parser *parser) static tree c_parser_std_attribute_specifier (c_parser *parser, bool for_tm) { + bool seen_deprecated = false; + bool seen_fallthrough = false; + bool seen_maybe_unused = false; location_t loc = c_parser_peek_token (parser)->location; if (!c_parser_require (parser, CPP_OPEN_SQUARE, "expected %<[%>")) return NULL_TREE; @@ -4898,8 +4901,55 @@ c_parser_std_attribute_specifier (c_parser *parser, bool for_tm) tree attribute = c_parser_std_attribute (parser); if (attribute != error_mark_node) { - TREE_CHAIN (attribute) = attributes; - attributes = attribute; + bool duplicate = false; + tree name = get_attribute_name (attribute); + tree ns = get_attribute_namespace (attribute); + if (ns == NULL_TREE) + { + /* Some standard attributes may appear at most once in + each attribute list. Diagnose duplicates and remove + them from the list to avoid subsequent diagnostics + such as the more general one for multiple + "fallthrough" attributes in the same place (including + in separate attribute lists in the same attribute + specifier sequence, which is not a constraint + violation). */ + if (is_attribute_p ("deprecated", name)) + { + if (seen_deprecated) + { + error ("attribute %<deprecated%> can appear at most " + "once in an attribute-list"); + duplicate = true; + } + seen_deprecated = true; + } + else if (is_attribute_p ("fallthrough", name)) + { + if (seen_fallthrough) + { + error ("attribute %<fallthrough%> can appear at most " + "once in an attribute-list"); + duplicate = true; + } + seen_fallthrough = true; + } + else if (is_attribute_p ("maybe_unused", name)) + { + if (seen_maybe_unused) + { + error ("attribute %<maybe_unused%> can appear at most " + "once in an attribute-list"); + duplicate = true; + } + seen_maybe_unused = true; + } + } + if (!duplicate) + { + TREE_CHAIN (attribute) = attributes; + attributes = attribute; + } } if (c_parser_next_token_is_not (parser, CPP_COMMA)) break; |