Hi!
My r15-7822 PR118787 change unfortunately broke build on x86_64-w64-mingw32.
The reduced testcase below shows what is going on.
va_list on this target is char * with extra (non-dependent) attributes
on it.
Before my r15-7822 change, instantiation of such type used the fast path and
just returned t, but as it has non-NULL TYPE_ATTRIBUTES, it now falls
through, builds a pointer type and then calls
apply_late_template_attributes. And in there triggers a bug, that function
has been written for types with RECORD_TYPE/UNION_TYPE (or ENUMERAL_TYPE?)
in mind, where we call apply_late_template_attributes with
ATTR_FLAG_TYPE_IN_PLACE and can just apply the non-dependent attributes
directly to TYPE_ATTRIBUTES. That is wrong for shared types like
{POINTER,REFERENCE,ARRAY}_TYPE etc., we should just force
cp_build_type_attribute_variant to build a variant type for the
non-dependent attributes and then process dependent attributes (which
given attr_flag will DTRT already).
The second change in the patch is an optimization, we can actually return
back to returning t even when TYPE_ATTRIBUTES is non-NULL, as long as it
is non-dependent (dependent attributes are stored first, so it is enough
to check the first attribute).
Bootstrapped/regtested on x86_64-linux and i686-linux and tested with
x86_64-linux -> x86_64-w64-mingw32 cross build (which failed before during
libstdc++-v3 build). Ok for trunk?
2025-03-06 Jakub Jelinek <ja...@redhat.com>
PR c++/119138
* pt.cc (apply_late_template_attributes): Set p to NULL if
ATTR_FLAG_TYPE_IN_PLACE is not set in attr_flags.
(tsubst) <case POINTER_TYPE, case REFERENCE_TYPE, case ARRAY_TYPE>:
Reuse original type even if TYPE_ATTRIBUTES is non-NULL, but all
the attributes are non-dependent.
* g++.dg/template/pr119138.C: New test.
--- gcc/cp/pt.cc.jj 2025-03-05 06:40:52.406421999 +0100
+++ gcc/cp/pt.cc 2025-03-06 11:54:10.127739493 +0100
@@ -12393,7 +12393,8 @@ apply_late_template_attributes (tree *de
to our attributes parameter. */
gcc_assert (*p == attributes);
}
- else if (FUNC_OR_METHOD_TYPE_P (*decl_p))
+ else if (FUNC_OR_METHOD_TYPE_P (*decl_p)
+ || (attr_flags & ATTR_FLAG_TYPE_IN_PLACE) == 0)
p = NULL;
else
{
@@ -16867,7 +16868,8 @@ tsubst (tree t, tree args, tsubst_flags_
{
if (type == TREE_TYPE (t)
&& TREE_CODE (type) != METHOD_TYPE
- && TYPE_ATTRIBUTES (t) == NULL_TREE)
+ && (TYPE_ATTRIBUTES (t) == NULL_TREE
+ || !ATTR_IS_DEPENDENT (TYPE_ATTRIBUTES (t))))
return t;
/* [temp.deduct]
@@ -17029,7 +17031,8 @@ tsubst (tree t, tree args, tsubst_flags_
it will obviously be the same as T. */
if (type == TREE_TYPE (t)
&& domain == TYPE_DOMAIN (t)
- && TYPE_ATTRIBUTES (t) == NULL_TREE)
+ && (TYPE_ATTRIBUTES (t) == NULL_TREE
+ || !ATTR_IS_DEPENDENT (TYPE_ATTRIBUTES (t))))
return t;
/* These checks should match the ones in create_array_type_for_decl.
--- gcc/testsuite/g++.dg/template/pr119138.C.jj 2025-03-06 11:29:17.811634125
+0100
+++ gcc/testsuite/g++.dg/template/pr119138.C 2025-03-06 12:04:02.077480568
+0100
@@ -0,0 +1,16 @@
+// PR c++/119138
+// { dg-do compile }
+
+#include <stdarg.h>
+
+template <typename>
+void
+foo (va_list)
+{
+}
+
+void
+bar (va_list ap)
+{
+ foo <char> (ap);
+}
Jakub
