[PATCH] c++: Fix ICE-on-invalid with broken attribute [PR93684]

[Marek Polacek]

We crash when parsing

  [[a::

because we see a CPP_SCOPE and then we're trying to consume a CPP_EOF
token.  So peek before consuming it.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

        PR c++/93684 - ICE-on-invalid with broken attribute.
        * parser.c (cp_parser_std_attribute): Peek a token first before
        consuming it.

        * g++.dg/parse/attr4.C: New test.
---
 gcc/cp/parser.c                    | 3 ++-
 gcc/testsuite/g++.dg/parse/attr4.C | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/parse/attr4.C

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 640affd8368..e8a536ae22f 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -26720,7 +26720,7 @@ cp_parser_std_attribute (cp_parser *parser, tree 
attr_ns)
                                   "with scoped attribute token");
       attr_ns = attr_id;
 
-      token = cp_lexer_consume_token (parser->lexer);
+      token = cp_lexer_peek_token (parser->lexer);
       if (token->type == CPP_NAME)
        attr_id = token->u.value;
       else if (token->type == CPP_KEYWORD)
@@ -26733,6 +26733,7 @@ cp_parser_std_attribute (cp_parser *parser, tree 
attr_ns)
                    "expected an identifier for the attribute name");
          return error_mark_node;
        }
+      cp_lexer_consume_token (parser->lexer);
 
       attr_ns = canonicalize_attr_name (attr_ns);
       attr_id = canonicalize_attr_name (attr_id);
diff --git a/gcc/testsuite/g++.dg/parse/attr4.C 
b/gcc/testsuite/g++.dg/parse/attr4.C
new file mode 100644
index 00000000000..7713fc96c64
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/attr4.C
@@ -0,0 +1,3 @@
+// PR c++/93684 - ICE-on-invalid with broken attribute.
+
+[[a:: // { dg-error "expected|expected" }

base-commit: ad21e0072e20b7c8e4d7af5ca78f24cc6ae407d1
-- 
Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA