The C++ front end wants to be able to build up objects of the various
typeinfo derived classes (such as __si_class_type_info) without needing
to see the full definition of the class. As part of this we build a
VAR_DECL for the vtable, but never define it because we don't actually
have declarations of the virtual functions, we're only using it for
external references. ctor_for_folding was assuming that all vtables are
defined, which broke on this case.
Tested x86_64-pc-linux-gnu. OK for trunk?
commit e13e596c640374df15c0a25d5049d5e30d08dc6b
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Jun 2 20:27:24 2014 -0400
PR c++/61020
* varpool.c (ctor_for_folding): Handle uninitialized vtables.
diff --git a/gcc/testsuite/g++.dg/opt/typeinfo1.C b/gcc/testsuite/g++.dg/opt/typeinfo1.C
new file mode 100644
index 0000000..efac4cb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/typeinfo1.C
@@ -0,0 +1,27 @@
+// PR c++/61020
+// { dg-options "-O2" }
+// { dg-do run }
+
+#include <typeinfo>
+
+struct Base {
+ virtual ~Base() { }
+};
+
+struct Derived : public Base {
+};
+
+int compare(const Base& base)
+{
+ return typeid(base) == typeid(typeid(Derived));
+}
+
+int main()
+{
+ Base base;
+ Derived derived;
+
+ if (compare(base)) return 1;
+ if (compare(derived)) return 2;
+ return 0;
+}
diff --git a/gcc/varpool.c b/gcc/varpool.c
index 1697bb4..143cd3b 100644
--- a/gcc/varpool.c
+++ b/gcc/varpool.c
@@ -306,7 +306,16 @@ ctor_for_folding (tree decl)
if (DECL_VIRTUAL_P (real_decl))
{
gcc_checking_assert (TREE_READONLY (real_decl));
- return DECL_INITIAL (real_decl);
+ if (DECL_INITIAL (real_decl))
+ return DECL_INITIAL (real_decl);
+ else
+ {
+ /* The C++ front end creates VAR_DECLs for vtables of typeinfo
+ classes not defined in the current TU so that it can refer
+ to them from typeinfo objects. Avoid returning NULL_TREE. */
+ gcc_checking_assert (!COMPLETE_TYPE_P (DECL_CONTEXT (real_decl)));
+ return error_mark_node;
+ }
}
/* If there is no constructor, we have nothing to do. */
