PR c++/85277 - ICE with invalid offsetof.

	* semantics.c (finish_offsetof): Avoid passing non-DECL to %qD.
	Adjust -Winvalid-offsetof diagnostic to say conditionally supported.

From-SVN: r259254

gcc/cp/ChangeLog

 2018-04-09  Jason Merrill  <jason@redhat.com>
 
+	PR c++/85277 - ICE with invalid offsetof.
+	* semantics.c (finish_offsetof): Avoid passing non-DECL to %qD.
+	Adjust -Winvalid-offsetof diagnostic to say conditionally supported.
+
 	PR c++/85264 - ICE with excess template-parameter-list.
 	* parser.c (cp_parser_check_template_parameters): Add template_id_p
 	parameter.  Don't allow an extra template header if true.

gcc/cp/semantics.c

@@ -4043,17 +4043,17 @@ finish_offsetof (tree object_ptr, tree expr, location_t loc)
       || TREE_CODE (TREE_TYPE (expr)) == METHOD_TYPE
       || TREE_TYPE (expr) == unknown_type_node)
     {
-      if (INDIRECT_REF_P (expr))
-	error ("second operand of %<offsetof%> is neither a single "
-	       "identifier nor a sequence of member accesses and "
-	       "array references");
-      else
+      while (TREE_CODE (expr) == COMPONENT_REF
+	     || TREE_CODE (expr) == COMPOUND_EXPR)
+	expr = TREE_OPERAND (expr, 1);
+
+      if (DECL_P (expr))
 	{
-	  if (TREE_CODE (expr) == COMPONENT_REF
-	      || TREE_CODE (expr) == COMPOUND_EXPR)
-	    expr = TREE_OPERAND (expr, 1);
 	  error ("cannot apply %<offsetof%> to member function %qD", expr);
+	  inform (DECL_SOURCE_LOCATION (expr), "declared here");
 	}
+      else
+	error ("cannot apply %<offsetof%> to member function");
       return error_mark_node;
     }
   if (TREE_CODE (expr) == CONST_DECL)
@@ -4069,9 +4069,9 @@ finish_offsetof (tree object_ptr, tree expr, location_t loc)
       && CLASS_TYPE_P (TREE_TYPE (TREE_TYPE (object_ptr)))
       && CLASSTYPE_NON_STD_LAYOUT (TREE_TYPE (TREE_TYPE (object_ptr)))
       && cp_unevaluated_operand == 0)
-    pedwarn (loc, OPT_Winvalid_offsetof,
-	     "offsetof within non-standard-layout type %qT is undefined",
-	     TREE_TYPE (TREE_TYPE (object_ptr)));
+    warning_at (loc, OPT_Winvalid_offsetof, "offsetof within "
+		"non-standard-layout type %qT is conditionally-supported",
+		TREE_TYPE (TREE_TYPE (object_ptr)));
   return fold_offsetof (expr);
 }
 

gcc/testsuite/g++.dg/ext/builtin-offsetof1.C

 // PR c++/51413
-// { dg-options "-w" }
+// PR c++/85277
+// { dg-options "-Wno-pointer-arith" }
 
 struct A
 {
   static void foo();
 };
 
-int i = __builtin_offsetof(A, foo[1]);  // { dg-error "neither a single identifier nor a sequence of member accesses and array references" }
+int i = __builtin_offsetof(A, foo[1]);  // { dg-error "offsetof" }
+int j = __builtin_offsetof(volatile A, foo[0]);  // { dg-error "offsetof" }

gcc/testsuite/g++.dg/other/offsetof3.C

@@ -12,4 +12,4 @@ protected:
 typedef X* pX;
 typedef __SIZE_TYPE__ size_t;
 
-size_t yoff = __builtin_offsetof (X, y); /* { dg-error "35:non-standard-layout" } */
+size_t yoff = __builtin_offsetof (X, y); /* { dg-message "35:non-standard-layout" } */

gcc/testsuite/g++.dg/other/offsetof5.C

@@ -9,14 +9,14 @@ struct A
   int &i;
 };
 
-int j = offsetof (A, i);		// { dg-error "offsetof" }
+int j = offsetof (A, i);		// { dg-message "offsetof" }
 
 template <typename T>
 struct S
 {
   T h;
   T &i;
-  static const int j = offsetof (S, i);	// { dg-error "offsetof" }
+  static const int j = offsetof (S, i);	// { dg-message "offsetof" }
 };
 
 int k = S<int>::j;			// { dg-message "required from here" }

gcc/testsuite/g++.dg/other/offsetof8.C

@@ -9,4 +9,4 @@ struct B: virtual A { };
 int a[]  = {
   !&((B*)0)->i,    // { dg-error "invalid access to non-static data member" }
   __builtin_offsetof (B, i)   // { dg-error "invalid access to non-static" }
-};			      // { dg-error "offsetof within non-standard-layout type" "" { target *-*-* } .-1 }
+};			      // { dg-message "offsetof within non-standard-layout type" "" { target *-*-* } .-1 }