[stdlib] Kill _swift_isUniquelyReferenced @asmname

Swift SVN r22576

stdlib/runtime/HeapObject.cpp

@@ -28,6 +28,7 @@
 #include <cstdio>
 #include <cstdlib>
 #include <unistd.h>
+#include "../shims/RuntimeShims.h"
 
 using namespace swift;
 
@@ -523,11 +524,15 @@ void swift::_swift_abortRetainUnowned(const void *object) {
   swift::crash("attempted to retain deallocated object");
 }
 
-// Given the bits of a Native swift object reference, or of a
-// word-sized Swift enum containing a Native swift object reference as
-// a payload, return true iff the object's strong reference count is
-// 1.
-extern "C" bool _swift_isUniquelyReferenced(std::uintptr_t bits) {
+//===----------------------------------------------------------------------===//
+// FIXME: this should return bool but it chokes the compiler
+// <rdar://problem/18573806>
+//===----------------------------------------------------------------------===//
+/// Given the bits of a Native swift object reference, or of a
+/// word-sized Swift enum containing a Native swift object reference as
+/// a payload, return true iff the object's strong reference count is
+/// 1.
+unsigned char swift::_swift_isUniquelyReferenced(std::uintptr_t bits) {
   const auto object = reinterpret_cast<HeapObject*>(
     bits & ~heap_object_abi::SwiftSpareBitsMask);