PR c++/79050 - ICE with undeduced auto and LTO

	* decl.c (poplevel): Remove undeduced auto decls.

From-SVN: r245510

gcc/cp/ChangeLog

+2017-02-16  Jason Merrill  <jason@redhat.com>
+
+	PR c++/79050 - ICE with undeduced auto and LTO
+	* decl.c (poplevel): Remove undeduced auto decls.
+
 2017-02-16  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/79512

gcc/cp/decl.c

@@ -792,14 +792,17 @@ poplevel (int keep, int reverse, int functionbody)
      back ends won't understand OVERLOAD, so we remove them here.
      Because the BLOCK_VARS are (temporarily) shared with
      CURRENT_BINDING_LEVEL->NAMES we must do this fixup after we have
-     popped all the bindings.  */
+     popped all the bindings.  Also remove undeduced 'auto' decls,
+     which LTO doesn't understand, and can't have been used by anything.  */
   if (block)
     {
       tree* d;
 
       for (d = &BLOCK_VARS (block); *d; )
 	{
-	  if (TREE_CODE (*d) == TREE_LIST)
+	  if (TREE_CODE (*d) == TREE_LIST
+	      || (!processing_template_decl
+		  && undeduced_auto_decl (*d)))
 	    *d = TREE_CHAIN (*d);
 	  else
 	    d = &DECL_CHAIN (*d);

gcc/testsuite/g++.dg/lto/pr79050_0.C

+// PR c++/79050
+// { dg-lto-do assemble }
+
+int main ()
+{
+  auto foo ();
+}