win: Fix InitializationStateDcheck in Release build

util/misc/initialization_state_dcheck.h

Index: util/misc/initialization_state_dcheck.h
diff --git a/util/misc/initialization_state_dcheck.h b/util/misc/initialization_state_dcheck.h
index 88f7ac1e9a946da993f348078a30c5ec111c2cd5..96d7cf1b4af09c287b3f3b293504489e07cf04e0 100644
--- a/util/misc/initialization_state_dcheck.h
+++ b/util/misc/initialization_state_dcheck.h
@@ -18,6 +18,7 @@
 //! \file
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "util/misc/initialization_state.h"
 
@@ -155,14 +156,9 @@ class InitializationStateDcheck : public InitializationState {
 #else
 
 // Since this is to be used as a DCHECK (for debugging), it should be
-// non-intrusive in non-DCHECK (non-debug, release) builds. An empty struct
-// would still have a nonzero size (rationale:

[Mark Mentovai, 2015/02/11 20:47:12]

This comment explains why this wasn’t done before.

Since MSVC doesn’t accept the zero-length, can we at least make this conditional
on COMPILER_MSVC, to avoid wasting these bytes where it’s not necessary?

[scottmg, 2015/02/11 21:03:31]

Done.

It seemed unnecessarily tricky to me given the size and number of objects in
which it was used.

-// http://www.stroustrup.com/bs_faq2.html#sizeof-empty). Zero-length arrays are
-// technically invalid according to the standard, but clang and g++ accept them
-// without complaint even with warnings turned up. They take up no space at all,
-// and they can be “initialized” with the same () syntax used to initialize
-// objects of the DCHECK_IS_ON InitializationStateDcheck class above.
-using InitializationStateDcheck = bool[0];
+// non-intrusive in non-DCHECK (non-debug, release) builds.
+struct InitializationStateDcheck {
+};
 
 namespace internal {
 
@@ -175,18 +171,14 @@ inline bool EatInitializationState(const InitializationStateDcheck*) {
 
 }  // namepspace internal
 
-// The contents of these DCHECKs will never be evaluated, but they make use of
-// initialization_state_dcheck to avoid triggering -Wunused-private-field
-// warnings.
+// Avoid triggering warnings by making repurposing these macros when DCHECKs are
+// disabled.
 #define INITIALIZATION_STATE_SET_INITIALIZING(initialization_state_dcheck) \
-  DCHECK(::crashpad::internal::EatInitializationState( \
-      &(initialization_state_dcheck)))
+  ALLOW_UNUSED_LOCAL(initialization_state_dcheck)
 #define INITIALIZATION_STATE_SET_VALID(initialization_state_dcheck) \
-  DCHECK(::crashpad::internal::EatInitializationState( \
-      &(initialization_state_dcheck)))
+  ALLOW_UNUSED_LOCAL(initialization_state_dcheck)
 #define INITIALIZATION_STATE_DCHECK_VALID(initialization_state_dcheck) \
-  DCHECK(::crashpad::internal::EatInitializationState( \
-      &(initialization_state_dcheck)))
+  ALLOW_UNUSED_LOCAL(initialization_state_dcheck)
 
 #endif