PR c++/79900 - ICE in strip_typedefs

	PR c++/79900 - ICE in strip_typedefs
	* tree.c (strip_typedefs): Skip the attribute handling if T is
	a variant type which hasn't been updated yet.

	* g++.dg/warn/Wpadded-1.C: New test.

From-SVN: r245988

gcc/cp/ChangeLog

+2017-03-09  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/79900 - ICE in strip_typedefs
+	* tree.c (strip_typedefs): Skip the attribute handling if T is
+	a variant type which hasn't been updated yet.
+
 2017-03-08  Jason Merrill  <jason@redhat.com>
 
 	PR c++/79797 - ICE with self-reference in array DMI.

gcc/cp/tree.c

@@ -1548,29 +1548,40 @@ strip_typedefs (tree t, bool *remove_attributes)
 	result = TYPE_MAIN_VARIANT (t);
     }
   gcc_assert (!typedef_variant_p (result));
-  if (TYPE_USER_ALIGN (t) != TYPE_USER_ALIGN (result)
-      || TYPE_ALIGN (t) != TYPE_ALIGN (result))
+
+  if (COMPLETE_TYPE_P (result) && !COMPLETE_TYPE_P (t))
+  /* If RESULT is complete and T isn't, it's likely the case that T
+     is a variant of RESULT which hasn't been updated yet.  Skip the
+     attribute handling.  */;
+  else
     {
-      gcc_assert (TYPE_USER_ALIGN (t));
-      if (remove_attributes)
-	*remove_attributes = true;
-      else
+      if (TYPE_USER_ALIGN (t) != TYPE_USER_ALIGN (result)
+	  || TYPE_ALIGN (t) != TYPE_ALIGN (result))
 	{
-	  if (TYPE_ALIGN (t) == TYPE_ALIGN (result))
-	    result = build_variant_type_copy (result);
+	  gcc_assert (TYPE_USER_ALIGN (t));
+	  if (remove_attributes)
+	    *remove_attributes = true;
 	  else
-	    result = build_aligned_type (result, TYPE_ALIGN (t));
-	  TYPE_USER_ALIGN (result) = true;
+	    {
+	      if (TYPE_ALIGN (t) == TYPE_ALIGN (result))
+		result = build_variant_type_copy (result);
+	      else
+		result = build_aligned_type (result, TYPE_ALIGN (t));
+	      TYPE_USER_ALIGN (result) = true;
+	    }
+	}
+
+      if (TYPE_ATTRIBUTES (t))
+	{
+	  if (remove_attributes)
+	    result = apply_identity_attributes (result, TYPE_ATTRIBUTES (t),
+						remove_attributes);
+	  else
+	    result = cp_build_type_attribute_variant (result,
+						      TYPE_ATTRIBUTES (t));
 	}
     }
-  if (TYPE_ATTRIBUTES (t))
-    {
-      if (remove_attributes)
-	result = apply_identity_attributes (result, TYPE_ATTRIBUTES (t),
-					    remove_attributes);
-      else
-	result = cp_build_type_attribute_variant (result, TYPE_ATTRIBUTES (t));
-    }
+
   return cp_build_qualified_type (result, cp_type_quals (t));
 }
 

gcc/testsuite/ChangeLog

+2017-03-09  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/79900 - ICE in strip_typedefs
+	* g++.dg/warn/Wpadded-1.C: New test.
+
 2017-03-08  Marek Polacek  <polacek@redhat.com>
 
 	* g++.dg/Walloca1.C: Adjust dg-warning.

gcc/testsuite/g++.dg/warn/Wpadded-1.C

+// PR c++/79900 - ICE in strip_typedefs
+// { dg-do compile }
+// { dg-options "-Wpadded" }
+
+template <class> struct A;
+template <typename> struct B { // { dg-warning "padding struct size to alignment boundary" }
+  long _M_off;
+  int _M_state;
+};
+template <> struct A<char> { typedef B<int> pos_type; };
+enum _Ios_Openmode {};
+struct C {
+  typedef _Ios_Openmode openmode;
+};
+template <typename, typename _Traits> struct D {
+  typedef typename _Traits::pos_type pos_type;
+  pos_type m_fn1(pos_type, C::openmode);
+};
+template class D<char, A<char> >;
+template <typename _CharT, typename _Traits>
+typename D<_CharT, _Traits>::pos_type D<_CharT, _Traits>::m_fn1(pos_type x,
+                                                                C::openmode) { return x; }