re PR c/89933 (ICE in merge_decls, at c/c-decl.c:2517)

	PR c/89933
c/
	* c-decl.c (merge_decls): When newdecl's type is its main variant,
	don't try to remove it from the variant list, but instead assert
	it has no variants.
cp/
	* decl.c (duplicate_decls): When newdecl's type is its main variant,
	don't try to remove it from the variant list, but instead assert
	it has no variants.
testsuite/
	* c-c++-common/pr89933.c: New test.

From-SVN: r270329

gcc/c/ChangeLog

+2019-04-12  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/89933
+	* c-decl.c (merge_decls): When newdecl's type is its main variant,
+	don't try to remove it from the variant list, but instead assert
+	it has no variants.
+
 2019-04-01  Richard Biener  <rguenther@suse.de>
 
 	PR c/71598

gcc/c/c-decl.c

@@ -2512,6 +2512,9 @@ merge_decls (tree newdecl, tree olddecl, tree newtype, tree oldtype)
       if (TYPE_NAME (TREE_TYPE (newdecl)) == newdecl)
 	{
 	  tree remove = TREE_TYPE (newdecl);
+	  if (TYPE_MAIN_VARIANT (remove) == remove)
+	    gcc_assert (TYPE_NEXT_VARIANT (remove) == NULL_TREE);
+	  else
 	    for (tree t = TYPE_MAIN_VARIANT (remove); ;
 		 t = TYPE_NEXT_VARIANT (t))
 	      if (TYPE_NEXT_VARIANT (t) == remove)

gcc/cp/ChangeLog

+2019-04-12  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/89933
+	* decl.c (duplicate_decls): When newdecl's type is its main variant,
+	don't try to remove it from the variant list, but instead assert
+	it has no variants.
+
 2019-04-12  Martin Sebor  <msebor@redhat.com>
 
 	PR c/88383

gcc/cp/decl.c

@@ -2132,6 +2132,9 @@ next_arg:;
 	  if (TYPE_NAME (TREE_TYPE (newdecl)) == newdecl)
 	    {
 	      tree remove = TREE_TYPE (newdecl);
+	      if (TYPE_MAIN_VARIANT (remove) == remove)
+		gcc_assert (TYPE_NEXT_VARIANT (remove) == NULL_TREE);
+	      else
 		for (tree t = TYPE_MAIN_VARIANT (remove); ;
 		     t = TYPE_NEXT_VARIANT (t))
 		  if (TYPE_NEXT_VARIANT (t) == remove)

gcc/testsuite/ChangeLog

+2019-04-12  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/89933
+	* c-c++-common/pr89933.c: New test.
+
 2019-04-12  Martin Sebor  <msebor@redhat.com>
 
 	PR c/88383

gcc/testsuite/c-c++-common/pr89933.c

+/* PR c/89933 */
+/* { dg-do compile } */
+
+typedef unsigned int a __attribute__ ((__aligned__(8), __may_alias__));
+typedef unsigned int a __attribute__ ((__aligned__(8), __may_alias__));