re PR go/86343 (types built by GO share TYPE_FIELDS in unsupported way)

	PR go/86343
	* go-gcc.cc (Gcc_backend::set_placeholder_struct_type): Go back to
	build_distinct_type_copy, but copy the fields so that they have
	the right DECL_CONTEXT.

From-SVN: r267789

gcc/go/ChangeLog

+2019-01-09  Ian Lance Taylor  <iant@golang.org>
+
+	PR go/86343
+	* go-gcc.cc (Gcc_backend::set_placeholder_struct_type): Go back to
+	build_distinct_type_copy, but copy the fields so that they have
+	the right DECL_CONTEXT.
+
 2019-01-09  Sandra Loosemore  <sandra@codesourcery.com>
 
 	PR other/16615

gcc/go/go-gcc.cc

@@ -1098,9 +1098,13 @@ Gcc_backend::set_placeholder_struct_type(
   if (TYPE_NAME(t) != NULL_TREE)
     {
       // Build the data structure gcc wants to see for a typedef.
-      tree copy = build_variant_type_copy(t);
+      tree copy = build_distinct_type_copy(t);
       TYPE_NAME(copy) = NULL_TREE;
       DECL_ORIGINAL_TYPE(TYPE_NAME(t)) = copy;
+      TYPE_SIZE(copy) = NULL_TREE;
+      Btype* bc = this->make_type(copy);
+      this->fill_in_struct(bc, fields);
+      delete bc;
     }
 
   return r->get_tree() != error_mark_node;