re PR c/43125 (Revision 156907 failed gcc.dg/attr-used.c)

	PR middle-end/43125
	* c-decl.c (merge_decls): Merge DECL_PRESERVE_P.

From-SVN: r156927

gcc/ChangeLog

@@ -37,6 +37,9 @@
 
 2010-02-19  Mike Stump  <mikestump@comcast.net>
 
+	PR middle-end/43125
+	* c-decl.c (merge_decls): Merge DECL_PRESERVE_P.
+
 	PR objc/43061
 	* cgraphunit.c (process_function_and_variable_attributes): Check
 	DECL_PRESERVE_P instead of looking up attribute "used".

gcc/c-decl.c

@@ -2387,6 +2387,10 @@ merge_decls (tree newdecl, tree olddecl, tree newtype, tree oldtype)
     TREE_USED (newdecl) = 1;
   else if (TREE_USED (newdecl))
     TREE_USED (olddecl) = 1;
+  if (DECL_PRESERVE_P (olddecl))
+    DECL_PRESERVE_P (newdecl) = 1;
+  else if (DECL_PRESERVE_P (newdecl))
+    DECL_PRESERVE_P (olddecl) = 1;
 
   /* Copy most of the decl-specific fields of NEWDECL into OLDDECL.
      But preserve OLDDECL's DECL_UID, DECL_CONTEXT and