internal error in _bfd_default_error_handler

[Alan Modra <amodra at gmail dot com>]

This fixes an internal error in _bfd_default_error_handler due to
old_bfd in elf_link_add_object_symbols being NULL when passed as a
warning message argument.  Triggered by accidentally trying to link a
mix of big-endian and little-endian PowerPC64 objects with duplicate
weak functions of different sizes.

	* elflink.c (_bfd_elf_merge_symbol): Set *poldbfd, *poldweak,
	and *poldalignment before exiting when !relocs_compatible.

Index: bfd/elflink.c
===================================================================
RCS file: /cvs/src/src/bfd/elflink.c,v
retrieving revision 1.497
diff -u -p -r1.497 elflink.c
--- bfd/elflink.c	21 Aug 2013 03:45:44 -0000	1.497
+++ bfd/elflink.c	21 Aug 2013 03:59:51 -0000
@@ -951,11 +951,6 @@ _bfd_elf_merge_symbol (bfd *abfd,
 
   bed = get_elf_backend_data (abfd);
 
-  /* This code is for coping with dynamic objects, and is only useful
-     if we are doing an ELF link.  */
-  if (!(*bed->relocs_compatible) (abfd->xvec, info->output_bfd->xvec))
-    return TRUE;
-
   /* For merging, we only care about real symbols.  But we need to make
      sure that indirect symbol dynamic flags are updated.  */
   hi = h;
@@ -963,6 +958,49 @@ _bfd_elf_merge_symbol (bfd *abfd,
 	 || h->root.type == bfd_link_hash_warning)
     h = (struct elf_link_hash_entry *) h->root.u.i.link;
 
+  /* OLDBFD and OLDSEC are a BFD and an ASECTION associated with the
+     existing symbol.  */
+
+  oldbfd = NULL;
+  oldsec = NULL;
+  switch (h->root.type)
+    {
+    default:
+      break;
+
+    case bfd_link_hash_undefined:
+    case bfd_link_hash_undefweak:
+      oldbfd = h->root.u.undef.abfd;
+      break;
+
+    case bfd_link_hash_defined:
+    case bfd_link_hash_defweak:
+      oldbfd = h->root.u.def.section->owner;
+      oldsec = h->root.u.def.section;
+      break;
+
+    case bfd_link_hash_common:
+      oldbfd = h->root.u.c.p->section->owner;
+      oldsec = h->root.u.c.p->section;
+      if (pold_alignment)
+	*pold_alignment = h->root.u.c.p->alignment_power;
+      break;
+    }
+  if (poldbfd && *poldbfd == NULL)
+    *poldbfd = oldbfd;
+
+  /* Differentiate strong and weak symbols.  */
+  newweak = bind == STB_WEAK;
+  oldweak = (h->root.type == bfd_link_hash_defweak
+	     || h->root.type == bfd_link_hash_undefweak);
+  if (pold_weak)
+    *pold_weak = oldweak;
+
+  /* This code is for coping with dynamic objects, and is only useful
+     if we are doing an ELF link.  */
+  if (!(*bed->relocs_compatible) (abfd->xvec, info->output_bfd->xvec))
+    return TRUE;
+
   /* We have to check it for every instance since the first few may be
      references and not all compilers emit symbol type for undefined
      symbols.  */
@@ -1007,45 +1045,6 @@ _bfd_elf_merge_symbol (bfd *abfd,
       return TRUE;
     }
 
-  /* OLDBFD and OLDSEC are a BFD and an ASECTION associated with the
-     existing symbol.  */
-
-  switch (h->root.type)
-    {
-    default:
-      oldbfd = NULL;
-      oldsec = NULL;
-      break;
-
-    case bfd_link_hash_undefined:
-    case bfd_link_hash_undefweak:
-      oldbfd = h->root.u.undef.abfd;
-      oldsec = NULL;
-      break;
-
-    case bfd_link_hash_defined:
-    case bfd_link_hash_defweak:
-      oldbfd = h->root.u.def.section->owner;
-      oldsec = h->root.u.def.section;
-      break;
-
-    case bfd_link_hash_common:
-      oldbfd = h->root.u.c.p->section->owner;
-      oldsec = h->root.u.c.p->section;
-      if (pold_alignment)
-	*pold_alignment = h->root.u.c.p->alignment_power;
-      break;
-    }
-  if (poldbfd && *poldbfd == NULL)
-    *poldbfd = oldbfd;
-
-  /* Differentiate strong and weak symbols.  */
-  newweak = bind == STB_WEAK;
-  oldweak = (h->root.type == bfd_link_hash_defweak
-	     || h->root.type == bfd_link_hash_undefweak);
-  if (pold_weak)
-    *pold_weak = oldweak;
-
   /* In cases involving weak versioned symbols, we may wind up trying
      to merge a symbol with itself.  Catch that here, to avoid the
      confusion that results if we try to override a symbol with

-- 
Alan Modra
Australia Development Lab, IBM