[gcc r13-24] c++: typeid and instantiation [PR102651]

[gcc r13-24] c++: typeid and instantiation [PR102651]

[Jason Merrill]

https://gcc.gnu.org/g:97b30a399ef561f6f37a2c08c830fdf3141bb504

commit r13-24-g97b30a399ef561f6f37a2c08c830fdf3141bb504
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Apr 15 00:11:00 2022 -0400

    c++: typeid and instantiation [PR102651]
    
    PR49387 was a problem with initially asking for a typeid for a class
    template specialization before it was complete, and later actually filling
    in the descriptor when the class was complete, and thus disagreeing on the
    form of the descriptor.  I fixed that by forcing the class to be complete,
    but this testcase shows why that approach is problematic.  So instead let's
    adjust the type of the descriptor later if needed.
    
            PR c++/102651
            PR c++/49387
    
    gcc/cp/ChangeLog:
    
            * rtti.cc (get_tinfo_decl_direct): Don't complete_type.
            (emit_tinfo_decl): Update tdesc type if needed.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/rtti/typeid-complete1.C: New test.

Diff:
---
 gcc/cp/rtti.cc                               | 15 +++++++++++----
 gcc/testsuite/g++.dg/rtti/typeid-complete1.C | 14 ++++++++++++++
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/gcc/cp/rtti.cc b/gcc/cp/rtti.cc
index a4dedc31f0a..f5b43ec0fb2 100644
--- a/gcc/cp/rtti.cc
+++ b/gcc/cp/rtti.cc
@@ -446,9 +446,6 @@ get_tinfo_decl_direct (tree type, tree name, int pseudo_ix)
 
   gcc_checking_assert (TREE_CODE (type) != METHOD_TYPE);
 
-  if (pseudo_ix < 0)
-    type = complete_type (type);
-
   if (CLASS_TYPE_P (type))
     d = CLASSTYPE_TYPEINFO_VAR (TYPE_MAIN_VARIANT (type));
 
@@ -1693,7 +1690,17 @@ emit_tinfo_decl (tree decl)
       tree init;
 
       DECL_EXTERNAL (decl) = 0;
-      init = get_pseudo_ti_init (type, get_pseudo_ti_index (type));
+      int pseudo_ix = get_pseudo_ti_index (type);
+      const tinfo_s *ti = get_tinfo_desc (pseudo_ix);
+      if (TREE_TYPE (decl) != ti->type)
+	{
+	  /* If the class became complete since we first called get_tinfo_decl,
+	     its type_info descriptor may have switched from __class_type_info
+	     to e.g. __si_class_type_info.  */
+	  TREE_TYPE (decl) = ti->type;
+	  relayout_decl (decl);
+	}
+      init = get_pseudo_ti_init (type, pseudo_ix);
       DECL_INITIAL (decl) = init;
       mark_used (decl);
       cp_finish_decl (decl, init, false, NULL_TREE, 0);
diff --git a/gcc/testsuite/g++.dg/rtti/typeid-complete1.C b/gcc/testsuite/g++.dg/rtti/typeid-complete1.C
new file mode 100644
index 00000000000..8d3fec46801
--- /dev/null
+++ b/gcc/testsuite/g++.dg/rtti/typeid-complete1.C
@@ -0,0 +1,14 @@
+// PR c++/102651
+
+#include <typeinfo>
+
+template <typename T>
+struct S : T{
+    T x;
+};
+
+const void *p;
+int main()
+{
+  p = &typeid( S<void>** );
+}