gccgo patch committed: Permit conversion from any uintptr type to unsafe.Pointer

[Ian Lance Taylor <iant@golang.org>]

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The Go language permits converting any type whose underlying type is
uintptr to unsafe.Pointer.  The Go frontend did not implement this
correctly.  This is http://golang.org/issue/10284.  This patch from
Minux fixes the problem.  Bootstrapped and ran Go testsuite on
x86_64-unknown-linux-gnu.  Committed to mainline.

A test case is being added to the main Go repository
(http://golang.org/cl/8240) and will be copied into the gccgo
testsuite in due course.

Ian

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diff -r d902a931d05b go/types.cc
--- a/go/types.cc	Mon Mar 30 10:26:47 2015 -0700
+++ b/go/types.cc	Mon Mar 30 10:30:14 2015 -0700
@@ -772,16 +772,16 @@
     }
 
   // An unsafe.Pointer type may be converted to any pointer type or to
-  // uintptr, and vice-versa.
+  // a type whose underlying type is uintptr, and vice-versa.
   if (lhs->is_unsafe_pointer_type()
       && (rhs->points_to() != NULL
 	  || (rhs->integer_type() != NULL
-	      && rhs->forwarded() == Type::lookup_integer_type("uintptr"))))
+	      && rhs->integer_type() == Type::lookup_integer_type("uintptr")->real_type())))
     return true;
   if (rhs->is_unsafe_pointer_type()
       && (lhs->points_to() != NULL
 	  || (lhs->integer_type() != NULL
-	      && lhs->forwarded() == Type::lookup_integer_type("uintptr"))))
+	      && lhs->integer_type() == Type::lookup_integer_type("uintptr")->real_type())))
     return true;
 
   // Give a better error message.