Fixed subtle difference in behavior between DCHECK and DCHECK_EQ et al.

base/logging.h

 // Copyright (c) 2010 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_
 #pragma once
 
 #include <string>
 #include <cstring>
@@ skipping 513 matching lines @@
 #else
 // Otherwise, we're a debug build so enable DLOGs and DCHECKs.
 #define ENABLE_DLOG 1
 #define ENABLE_DCHECK 1
 #endif
 
 // Definitions for DLOG et al.
 
 #if ENABLE_DLOG
 
+#define DLOG_IS_ON(severity) LOG_IS_ON(severity)
 #define DLOG_IF(severity, condition) LOG_IF(severity, condition)
 #define DLOG_ASSERT(condition) LOG_ASSERT(condition)
 #define DPLOG_IF(severity, condition) PLOG_IF(severity, condition)
 #define DVLOG_IF(verboselevel, condition) VLOG_IF(verboselevel, condition)
 
 #else  // ENABLE_DLOG
 
 // If ENABLE_DLOG is off, we want to avoid emitting any references to
 // |condition| (which may reference a variable defined only if NDEBUG
 // is not defined).  Contrast this with DCHECK et al., which has
 // different behavior.
 
 #define DLOG_EAT_STREAM_PARAMETERS                                      \
   true ? (void) 0 : ::logging::LogMessageVoidify() & LOG_STREAM(FATAL)
 
+#define DLOG_IS_ON(severity) false
 #define DLOG_IF(severity, condition) DLOG_EAT_STREAM_PARAMETERS
 #define DLOG_ASSERT(condition) DLOG_EAT_STREAM_PARAMETERS
 #define DPLOG_IF(severity, condition) DLOG_EAT_STREAM_PARAMETERS
 #define DVLOG_IF(verboselevel, condition) DLOG_EAT_STREAM_PARAMETERS
 
 #endif  // ENABLE_DLOG
 
 // DEBUG_MODE is for uses like
 //   if (DEBUG_MODE) foo.CheckThatFoo();
 // instead of
 //   #ifndef NDEBUG
 //     foo.CheckThatFoo();
 //   #endif
 //
 // We tie its state to ENABLE_DLOG.
 enum { DEBUG_MODE = ENABLE_DLOG };
 
 #undef ENABLE_DLOG
 
-#define DLOG_IS_ON(severity) (::logging::DEBUG_MODE && LOG_IS_ON(severity))
-
 #define DLOG(severity)                                          \
   LAZY_STREAM(LOG_STREAM(severity), DLOG_IS_ON(severity))
 
 #if defined(OS_WIN)
 #define DLOG_GETLASTERROR(severity) \
   LAZY_STREAM(LOG_GETLASTERROR_STREAM(severity), DLOG_IS_ON(severity))
 #define DLOG_GETLASTERROR_MODULE(severity, module)                      \
   LAZY_STREAM(LOG_GETLASTERROR_STREAM(severity, module),                \
               DLOG_IS_ON(severity))
 #elif defined(OS_POSIX)
 #define DLOG_ERRNO(severity)                                    \
   LAZY_STREAM(LOG_ERRNO_STREAM(severity), DLOG_IS_ON(severity))
 #endif
 
 #define DPLOG(severity)                                         \
   LAZY_STREAM(PLOG_STREAM(severity), DLOG_IS_ON(severity))
 
 #define DVLOG(verboselevel) DLOG_IF(INFO, VLOG_IS_ON(verboselevel))
 
 // Definitions for DCHECK et al.
 
 #if ENABLE_DCHECK
 
 #if defined(NDEBUG)
 
-// Set to true in InitLogging when we want to enable the dchecks in release.
-extern bool g_enable_dcheck;
-#define DCHECK_IS_ON() (::logging::g_enable_dcheck)
 #define DCHECK_SEVERITY ERROR_REPORT
 const LogSeverity LOG_DCHECK = LOG_ERROR_REPORT;
+// This is set to true in InitLogging when we want to enable the
+// DCHECKs in release.
+extern bool g_enable_dcheck;
+#define DCHECK_IS_ON() (::logging::g_enable_dcheck && LOG_IS_ON(DCHECK))
 
 #else  // defined(NDEBUG)
 
-// On a regular debug build, we want to have DCHECKS enabled.
-#define DCHECK_IS_ON() (true)
+// On a regular debug build, we want to have DCHECKs enabled.
 #define DCHECK_SEVERITY FATAL
 const LogSeverity LOG_DCHECK = LOG_FATAL;
+// TODO(akalin): We don't define this as 'true' since if the log level
+// is above FATAL, the DCHECK won't go through anyway.  Make it so
+// that DCHECKs work regardless of the logging level, then set this to
+// 'true'.
+#define DCHECK_IS_ON() LOG_IS_ON(DCHECK)
 
 #endif  // defined(NDEBUG)
 
 #else  // ENABLE_DCHECK
 
-#define DCHECK_IS_ON() (false)
 #define DCHECK_SEVERITY FATAL
 const LogSeverity LOG_DCHECK = LOG_FATAL;
+#define DCHECK_IS_ON() false
 
 #endif  // ENABLE_DCHECK
+#undef ENABLE_DCHECK
 
 // Unlike CHECK et al., DCHECK et al. *does* evaluate their arguments
 // lazily.
 
 // DCHECK et al. also make sure to reference |condition| regardless of
 // whether DCHECKs are enabled; this is so that we don't get unused
 // variable warnings if the only use of a variable is in a DCHECK.
 // This behavior is different from DLOG_IF et al.
 
 #define DCHECK(condition)                       \
   !DCHECK_IS_ON() ? (void) 0 :                  \
   LOG_IF(DCHECK_SEVERITY, !(condition))         \
   << "Check failed: " #condition ". "
 
 #define DPCHECK(condition)                      \
   !DCHECK_IS_ON() ? (void) 0 :                  \
   PLOG_IF(DCHECK_SEVERITY, !(condition))        \
   << "Check failed: " #condition ". "
 
 // Helper macro for binary operators.
 // Don't use this macro directly in your code, use DCHECK_EQ et al below.
 #define DCHECK_OP(name, op, val1, val2)                         \
-  if (DLOG_IS_ON(DCHECK_SEVERITY))                              \
+  if (DCHECK_IS_ON())                                           \
     if (logging::CheckOpString _result =                        \
         logging::Check##name##Impl((val1), (val2),              \
                                    #val1 " " #op " " #val2))    \
       logging::LogMessage(                                      \
           __FILE__, __LINE__, ::logging::LOG_DCHECK,            \
           _result).stream()
 
 // Equality/Inequality checks - compare two values, and log a LOG_FATAL message
 // including the two values when the result is not as expected.  The values
 // must have operator<<(ostream, ...) defined.
@@ skipping 283 matching lines @@
 #elif NOTIMPLEMENTED_POLICY == 4
 #define NOTIMPLEMENTED() LOG(ERROR) << NOTIMPLEMENTED_MSG
 #elif NOTIMPLEMENTED_POLICY == 5
 #define NOTIMPLEMENTED() do {\
   static int count = 0;\
   LOG_IF(ERROR, 0 == count++) << NOTIMPLEMENTED_MSG;\
 } while(0)
 #endif
 
 #endif  // BASE_LOGGING_H_