On 5/7/20 5:03 PM, Marek Polacek via Gcc-patches wrote:
On Wed, Jan 29, 2020 at 10:06:51PM +0100, Paolo Carlini wrote:
Hi,
On 29/01/20 19:00, Jason Merrill wrote:
On 1/29/20 4:31 AM, Paolo Carlini wrote:
Hi,
in this regression we issue a diagnostic about an incomplete type
(only a warning by default) and then we crash when we try to query
has_attribute on a member of the type because in such cases the
member remains an IDENTIFIER_NODE which of course doesn't have a
TREE_TYPE neither a DECL_ATTRIBUTES... Simply recognizing
IDENTIFIER_NODEs and returning false works fine, not sure if we want
to do something more sophisticated. Tested x86_64-linux.
Why are we getting to has_attribute at all for a type-dependent argument?
Because the implementation of __builtin_has_attribute, largely shared with
the C front-end, doesn't know about templates at all? :-/
Not sure it's the best time to complete it, but shouldn't be too difficult.
This ICEs even with a more reasonable test like
template<typename T>
void foo ()
{
static_assert(!__builtin_has_attribute(T::a, aligned));
}
The problem here is that __builtin_has_attribute doesn't handle type-dependent
arguments at all. To handle type-dependent arguments we'd have to introduce
a new template code, like STATIC_ASSERT or ADDRESSOF_EXPR (or a new generic
template code for built-ins?), but that's always a pain.
Or, meanwhile, we could just sorry. Martin, what do you think?
I never did implement the template handling and I didn't think to put
in a stopgap like the one below. It makes sense until I get around to
implementing it, hopefully for GCC 11.
Thanks!
Martin
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -8682,7 +8682,12 @@ cp_parser_has_attribute_expression (cp_parser *parser)
location_t atloc = cp_lexer_peek_token (parser->lexer)->location;
if (tree attr = cp_parser_gnu_attribute_list (parser, /*exactly_one=*/true))
{
- if (oper != error_mark_node)
+ if (oper == error_mark_node)
+ /* Nothing. */;
+ else if (type_dependent_expression_p (oper))
+ sorry_at (atloc, "%<__builtin_has_attribute%> with dependent argument "
+ "not supported yet");
+ else
{
/* Fold constant expressions used in attributes first. */
cp_check_const_attributes (attr);
Marek
