[gcc(refs/vendors/redhat/heads/gcc-8-branch)] backport: re PR c++/92648 (Handling of unknown attributes)

[Jakub Jelinek]

https://gcc.gnu.org/g:e9eb1e4611bc59b981f2be0d863a706e7e1d956a

commit e9eb1e4611bc59b981f2be0d863a706e7e1d956a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Feb 14 12:48:05 2020 +0100

    backport: re PR c++/92648 (Handling of unknown attributes)
    
            Backported from mainline
            2019-11-26  Jakub Jelinek  <jakub@redhat.com>
    
            PR c++/92648
            * parser.c (cp_parser_std_attribute): For unknown attributes,
            skip balanced token seq instead of trying to parse
            attribute-argument-clause as expression list.
    
            * g++.dg/cpp0x/gen-attrs-71.C: New test.

Diff:
---
 gcc/cp/ChangeLog                          |  5 +++++
 gcc/cp/parser.c                           | 12 ++++++++++++
 gcc/testsuite/g++.dg/cpp0x/gen-attrs-71.C |  7 +++++++
 3 files changed, 24 insertions(+)

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index dc658330588..b7f28bb8191 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -3,6 +3,11 @@
 	Backported from mainline
 	2019-11-26  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/92648
+	* parser.c (cp_parser_std_attribute): For unknown attributes,
+	skip balanced token seq instead of trying to parse
+	attribute-argument-clause as expression list.
+
 	PR c++/61414
 	* class.c (enum_to_min_precision): New hash_map.
 	(enum_min_precision): New function.
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index f523c87a9ae..cd71e149f81 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -2646,6 +2646,7 @@ static bool cp_parser_init_statement_p
   (cp_parser *);
 static bool cp_parser_skip_to_closing_square_bracket
   (cp_parser *);
+static size_t cp_parser_skip_balanced_tokens (cp_parser *, size_t);
 
 /* Concept-related syntactic transformations */
 
@@ -25400,6 +25401,17 @@ cp_parser_std_attribute (cp_parser *parser, tree attr_ns)
       /* A GNU attribute that takes an identifier in parameter.  */
       attr_flag = id_attr;
 
+    const attribute_spec *as
+      = lookup_attribute_spec (TREE_PURPOSE (attribute));
+    if (as == NULL)
+      {
+	/* For unknown attributes, just skip balanced tokens instead of
+	   trying to parse the arguments.  */
+	for (size_t n = cp_parser_skip_balanced_tokens (parser, 1) - 1; n; --n)
+	  cp_lexer_consume_token (parser->lexer);
+	return attribute;
+      }
+
     vec = cp_parser_parenthesized_expression_list
       (parser, attr_flag, /*cast_p=*/false,
        /*allow_expansion_p=*/true,
diff --git a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-71.C b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-71.C
new file mode 100644
index 00000000000..7876a2fba30
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-71.C
@@ -0,0 +1,7 @@
+// PR c++/92648
+// { dg-do compile { target c++11 } }
+
+int a [[gnu::no_such_attribute(![!(!)!]!,;;)]];	// { dg-warning "ignored" }
+int b [[no_such_namespace::nonexisting_attribute(linear(c, d : 2), reduction(*:e), linear(uval (f)))]];	// { dg-warning "ignored" }
+int c [[gnu::nonexisting_attribute()]];	// { dg-warning "ignored" }
+int d [[gnu::another_nonexistent_attr(1,"abcd",g+6)]];	// { dg-warning "ignored" }