Go patch committed: Function_type and Backend_function_type are not identical

[Ian Lance Taylor]

This patch by Cherry Zhang fixes the Go frontend so that Function_type
and Backend_function_type are not identical, since they have different
backend representations.  Bootstrapped and ran Go testsuite on
x86_64-pc-linux-gnu.  Committed to mainline.

Ian

Index: gcc/go/gofrontend/MERGE
===================================================================
--- gcc/go/gofrontend/MERGE     (revision 257171)
+++ gcc/go/gofrontend/MERGE     (working copy)
@@ -1,4 +1,4 @@
-bbce8a9af264b25c5f70bafb2ce95d4fed158d68
+a347356d0f432cafb69f0cc5833d27663736a042
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
Index: gcc/go/gofrontend/types.cc
===================================================================
--- gcc/go/gofrontend/types.cc  (revision 257069)
+++ gcc/go/gofrontend/types.cc  (working copy)
@@ -4442,6 +4442,9 @@ Function_type::is_identical(const Functi
                            Cmp_tags cmp_tags, bool errors_are_identical,
                            std::string* reason) const
 {
+  if (this->is_backend_function_type() != t->is_backend_function_type())
+    return false;
+
   if (!ignore_receiver)
     {
       const Typed_identifier* r1 = this->receiver();
Index: gcc/go/gofrontend/types.h
===================================================================
--- gcc/go/gofrontend/types.h   (revision 257069)
+++ gcc/go/gofrontend/types.h   (working copy)
@@ -2074,6 +2074,11 @@ class Function_type : public Type
   Btype*
   get_backend_fntype(Gogo*);
 
+  // Return whether this is a Backend_function_type.
+  virtual bool
+  is_backend_function_type() const
+  { return false; }
+
  protected:
   int
   do_traverse(Traverse*);
@@ -2167,6 +2172,12 @@ class Backend_function_type : public Fun
       : Function_type(receiver, parameters, results, location)
   { }
 
+  // Return whether this is a Backend_function_type. This overrides
+  // Function_type::is_backend_function_type.
+  bool
+  is_backend_function_type() const
+  { return true; }
+
  protected:
   Btype*
   do_get_backend(Gogo* gogo)