Protect macros from user code to the left of them

src/glog/logging.h.in

@@ -568,8 +568,10 @@ class LogSink;  // defined below
   LOG_TO_STRING_##severity(static_cast<std::vector<std::string>*>(outvec)).stream()
 
 #define LOG_IF(severity, condition) \
+  static_cast<void>(0),             \
   !(condition) ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
 #define SYSLOG_IF(severity, condition) \
+  static_cast<void>(0),                \
   !(condition) ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & SYSLOG(severity)
 
 #define LOG_ASSERT(condition)  \
@@ -859,6 +861,7 @@ DECLARE_CHECK_STROP_IMPL(strcasecmp, false)
       &@ac_google_namespace@::LogMessage::SendToLog)
 
 #define PLOG_IF(severity, condition) \
+  static_cast<void>(0),              \
   !(condition) ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & PLOG(severity)
 
 // A CHECK() macro that postpends errno if the condition is false. E.g.
@@ -1004,22 +1007,28 @@ const LogSeverity GLOG_0 = GLOG_ERROR;
 #else  // !DCHECK_IS_ON()
 
 #define DLOG(severity)  \
+  static_cast<void>(0), \
   true ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
 
 #define DVLOG(verboselevel)             \
-  (true || !VLOG_IS_ON(verboselevel)) ?\
+  static_cast<void>(0),                 \
+  (true || !VLOG_IS_ON(verboselevel)) ? \
       (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(INFO)
 
 #define DLOG_IF(severity, condition) \
+  static_cast<void>(0),              \
   (true || !(condition)) ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
 
 #define DLOG_EVERY_N(severity, n) \
+  static_cast<void>(0),           \
   true ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
 
 #define DLOG_IF_EVERY_N(severity, condition, n) \
+  static_cast<void>(0),                         \
   (true || !(condition))? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
 
 #define DLOG_ASSERT(condition) \
+  static_cast<void>(0),        \
   true ? (void) 0 : LOG_ASSERT(condition)
 
 // MSVC warning C4127: conditional expression is constant

src/windows/glog/logging.h

@@ -572,8 +572,10 @@ class LogSink;  // defined below
   LOG_TO_STRING_##severity(static_cast<std::vector<std::string>*>(outvec)).stream()
 
 #define LOG_IF(severity, condition) \
+  static_cast<void>(0),             \
   !(condition) ? (void) 0 : google::LogMessageVoidify() & LOG(severity)
 #define SYSLOG_IF(severity, condition) \
+  static_cast<void>(0),                \
   !(condition) ? (void) 0 : google::LogMessageVoidify() & SYSLOG(severity)
 
 #define LOG_ASSERT(condition)  \
@@ -863,6 +865,7 @@ DECLARE_CHECK_STROP_IMPL(strcasecmp, false)
       &google::LogMessage::SendToLog)
 
 #define PLOG_IF(severity, condition) \
+  static_cast<void>(0),              \
   !(condition) ? (void) 0 : google::LogMessageVoidify() & PLOG(severity)
 
 // A CHECK() macro that postpends errno if the condition is false. E.g.
@@ -1007,22 +1010,28 @@ const LogSeverity GLOG_0 = GLOG_ERROR;
 #else  // !DCHECK_IS_ON()
 
 #define DLOG(severity)  \
+  static_cast<void>(0), \
   true ? (void) 0 : google::LogMessageVoidify() & LOG(severity)
 
 #define DVLOG(verboselevel)             \
-  (true || !VLOG_IS_ON(verboselevel)) ?\
+  static_cast<void>(0),                 \
+  (true || !VLOG_IS_ON(verboselevel)) ? \
     (void) 0 : google::LogMessageVoidify() & LOG(INFO)
 
 #define DLOG_IF(severity, condition) \
+  static_cast<void>(0),              \
   (true || !(condition)) ? (void) 0 : google::LogMessageVoidify() & LOG(severity)
 
 #define DLOG_EVERY_N(severity, n) \
+  static_cast<void>(0),           \
   true ? (void) 0 : google::LogMessageVoidify() & LOG(severity)
 
 #define DLOG_IF_EVERY_N(severity, condition, n) \
+  static_cast<void>(0),                         \
   (true || !(condition))? (void) 0 : google::LogMessageVoidify() & LOG(severity)
 
 #define DLOG_ASSERT(condition) \
+  static_cast<void>(0),        \
   true ? (void) 0 : LOG_ASSERT(condition)
 
 // MSVC warning C4127: conditional expression is constant