Hi!
The C and C++ FEs disagree on what TYPE_NAME on RECORD_TYPE for
structure/class definition is (rather than typedef/using, for
those both have TYPE_NAME of TYPE_DECL with DECL_ORIGINAL_TYPE),
the C FE just uses IDENTIFIER_NODE as TYPE_NAME on RECORD_TYPE,
while the C++ FE uses TYPE_DECL as TYPENAME on RECORD_TYPE and
only DECL_NAME on the TYPE_DECL provides the IDENTIFIER_NODE.
The reason for the C++ FE way is that there can be type definitions
at class scope (rather than just typedefs) and those need to be
among TYPE_FIELDS (so the corresponding TYPE_DECL is in that chain)
etc.
The middle-end can cope with it, e.g.
if (TREE_CODE (TYPE_NAME (node)) == IDENTIFIER_NODE)
pp_tree_identifier (pp, TYPE_NAME (node));
else if (TREE_CODE (TYPE_NAME (node)) == TYPE_DECL
&& DECL_NAME (TYPE_NAME (node)))
dump_decl_name (pp, TYPE_NAME (node), flags);
and many other places.
Now, the backends on various targets create artificial structure
definitions for va_list, e.g. x86 creates struct __va_list_tag
and they do it the C++ FE way so that the C++ FE can cope with those.
Except the new c_type_tag can't deal with that and ICEs.
The following patch fixes it so that it can handle it too.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2025-11-27 Jakub Jelinek <[email protected]>
PR c/121506
* c-typeck.cc (c_type_tag): If TYPE_NAME is TYPE_DECL
with non-NULL DECL_NAME, return that.
* gcc.dg/pr121506.c: New test.
--- gcc/c/c-typeck.cc.jj 2025-11-11 07:21:30.449266914 +0100
+++ gcc/c/c-typeck.cc 2025-11-26 14:03:33.132153242 +0100
@@ -610,9 +610,9 @@ c_type_tag (const_tree t)
return NULL_TREE;
if (TREE_CODE (name) == TYPE_DECL)
{
- /* A TYPE_DECL added by add_decl_expr. */
- gcc_checking_assert (!DECL_NAME (name));
- return NULL_TREE;
+ if (!DECL_NAME (name))
+ return NULL_TREE;
+ name = DECL_NAME (name);
}
gcc_checking_assert (TREE_CODE (name) == IDENTIFIER_NODE);
return name;
--- gcc/testsuite/gcc.dg/pr121506.c.jj 2025-11-26 14:37:20.000040789 +0100
+++ gcc/testsuite/gcc.dg/pr121506.c 2025-11-26 14:36:56.632446029 +0100
@@ -0,0 +1,8 @@
+/* PR c/121506 */
+/* { dg-do compile } */
+
+#include <stdarg.h>
+
+struct A;
+void foo (struct A *); /* { dg-message "previous declaration of 'foo' with
type 'void\\\(struct A \\\*\\\)'" } */
+void foo (va_list); /* { dg-error "conflicting types for 'foo'; have" } */
Jakub
