Switch from template functions overloading to partial template specialization.

src/utils.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 742 matching lines @@
 // type of a variable of another type.  Of course the end result is likely to
 // be implementation dependent.  Most compilers (gcc-4.2 and MSVC 2005)
 // will completely optimize BitCast away.
 //
 // There is an additional use for BitCast.
 // Recent gccs will warn when they see casts that may result in breakage due to
 // the type-based aliasing rule.  If you have checked that there is no breakage
 // you can use BitCast to cast one pointer type to another.  This confuses gcc
 // enough that it can no longer see that you have cast one pointer type to
 // another thus avoiding the warning.
+
+// We need different implementations of BitCast for pointer and non-pointer
+// values. We use partial specialization of auxiliary struct to work around
+// issues with template functions overloading.
+template <class Dest, class Source>
+struct BitCastHelper {
+  STATIC_ASSERT(sizeof(Dest) == sizeof(Source));
+
+  INLINE(static Dest cast(const Source& source)) {
+    Dest dest;
+    memcpy(&dest, &source, sizeof(dest));
+    return dest;
+  }
+};
+
+template <class Dest, class Source>
+struct BitCastHelper<Dest, Source*> {
+  INLINE(static Dest cast(Source* source)) {
+    return BitCastHelper<Dest, uintptr_t>::
+        cast(reinterpret_cast<uintptr_t>(source));
+  }
+};
+

[Erik Corry, 2011/01/25 10:30:40]

Two blank lines.

 template <class Dest, class Source>
 inline Dest BitCast(const Source& source) {
-  // Compile time assertion: sizeof(Dest) == sizeof(Source)
-  // A compile error here means your Dest and Source have different sizes.
-  typedef char VerifySizesAreEqual[sizeof(Dest) == sizeof(Source) ? 1 : -1];
-
-  Dest dest;
-  memcpy(&dest, &source, sizeof(dest));
-  return dest;
-}
-
-template <class Dest, class Source>
-inline Dest BitCast(Source* source) {
-  return BitCast<Dest>(reinterpret_cast<uintptr_t>(source));
+  return BitCastHelper<Dest, Source>::cast(source);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_UTILS_H_