Improve EAT_STREAM_PARAMETERS for Windows x86

base/logging.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_LOGGING_H_
 #define BASE_LOGGING_H_
 
 #include <stddef.h>
 
 #include <cassert>
@@ skipping 408 matching lines @@
   COMPACT_GOOGLE_LOG_EX_ ## severity(ErrnoLogMessage, \
       ::logging::GetLastSystemErrorCode()).stream()
 #endif
 
 #define PLOG(severity)                                          \
   LAZY_STREAM(PLOG_STREAM(severity), LOG_IS_ON(severity))
 
 #define PLOG_IF(severity, condition) \
   LAZY_STREAM(PLOG_STREAM(severity), LOG_IS_ON(severity) && (condition))
 
-// The actual stream used isn't important.
-#define EAT_STREAM_PARAMETERS                                           \
-  true ? (void) 0 : ::logging::LogMessageVoidify() & LOG_STREAM(FATAL)
+extern std::ostream* g_swallow_stream;
+
+#define EAT_STREAM_PARAMETERS \

[dcheng, 2016/12/09 23:16:48]

Can we add a comment that mentions the subtleties involved here? I'm going to do
some language lawyering in the meantime to make sure this is considered OK.

[scottmg, 2016/12/09 23:30:26]

Sure. Are you concerned about not actually assigning to the pointer in the .cc
file? We could also easily do that to be safe if you think that's a good idea.

+  true ? (void)0              \
+       : ::logging::LogMessageVoidify() & (*::logging::g_swallow_stream)
 
 // Captures the result of a CHECK_EQ (for example) and facilitates testing as a
 // boolean.
 class CheckOpResult {
  public:
   // |message| must be non-null if and only if the check failed.
   CheckOpResult(std::string* message) : message_(message) {}
   // Returns true if the check succeeded.
   operator bool() const { return !message_; }
   // Returns the message.
@@ skipping 573 matching lines @@
 #elif NOTIMPLEMENTED_POLICY == 5
 #define NOTIMPLEMENTED() do {\
   static bool logged_once = false;\
   LOG_IF(ERROR, !logged_once) << NOTIMPLEMENTED_MSG;\
   logged_once = true;\
 } while(0);\
 EAT_STREAM_PARAMETERS
 #endif
 
 #endif  // BASE_LOGGING_H_