Go patch committed: Handle aliases to pointer types with interfaces

[Ian Lance Taylor via Gcc-patches]

The Go frontend miscompiled some cases where a program defined an
alias to a pointer type, and then tried to convert that type to an
interface type, or build a method table for that type.  This patch
fixes those problems.  The test case is https://golang.org/cl/241997.
Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu.  Committed
to mainline.

Ian

57fa4baf050ecfbd13fb8c74f7bae5cc2f98f977
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 64b13f410e0..c65fd8eecfc 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-2ad0970e9da95024110cd3244e9e21313af70a5f
+ce70fa16a73e3f162de01deab6b5d17783e6b76b
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/types.cc b/gcc/go/gofrontend/types.cc
index 3459a3357a3..7f65b4a5db2 100644
--- a/gcc/go/gofrontend/types.cc
+++ b/gcc/go/gofrontend/types.cc
@@ -9208,6 +9208,7 @@ Interface_type::implements_interface(const Type* t, 
std::string* reason) const
   if (this->all_methods_ == NULL)
     return true;
 
+  t = t->unalias();
   bool is_pointer = false;
   const Named_type* nt = t->named_type();
   const Struct_type* st = t->struct_type();
@@ -9220,6 +9221,7 @@ Interface_type::implements_interface(const Type* t, 
std::string* reason) const
        {
          // If T is a pointer to a named type, then we need to look at
          // the type to which it points.
+         pt = pt->unalias();
          is_pointer = true;
          nt = pt->named_type();
          st = pt->struct_type();
@@ -10408,19 +10410,24 @@ Named_type::interface_method_table(Interface_type* 
interface, bool is_pointer)
     return Expression::make_error(this->location_);
   if (this->is_alias_)
     {
-      if (this->type_->named_type() != NULL)
+      Type* t = this->type_;
+      if (!is_pointer && t->points_to() != NULL)
+       {
+         t = t->points_to();
+         is_pointer = true;
+       }
+      if (t->named_type() != NULL)
        {
          if (this->seen_alias_)
            return Expression::make_error(this->location_);
          this->seen_alias_ = true;
-         Named_type* nt = this->type_->named_type();
+         Named_type* nt = t->named_type();
          Expression* ret = nt->interface_method_table(interface, is_pointer);
          this->seen_alias_ = false;
          return ret;
        }
-      if (this->type_->struct_type() != NULL)
-       return this->type_->struct_type()->interface_method_table(interface,
-                                                                 is_pointer);
+      if (t->struct_type() != NULL)
+       return t->struct_type()->interface_method_table(interface, is_pointer);
       go_unreachable();
     }
   return Type::interface_method_table(this, interface, is_pointer,