Add Clang static analyzer to Clang toolchain defs in GN

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 708 matching lines @@
 #define DCHECK(condition)                                               \
   __analysis_assume(!!(condition)),                                     \
   LAZY_STREAM(LOG_STREAM(DCHECK), false)                                \
   << "Check failed: " #condition ". "
 
 #define DPCHECK(condition)                                              \
   __analysis_assume(!!(condition)),                                     \
   LAZY_STREAM(PLOG_STREAM(DCHECK), false)                               \
   << "Check failed: " #condition ". "
 
-#else  // _PREFAST_
+#elif defined(__clang_analyzer__)
+
+// Keeps the static analyzer from proceeding along the current codepath,
+// otherwise false positive errors may be generated  by null pointer checks.
+inline constexpr bool AnalyzerNoReturn() __attribute__((analyzer_noreturn)) {
+  return false;
+}
+
+#define DCHECK(condition)                                                   \
+  LAZY_STREAM(                                                              \
+      LOG_STREAM(DCHECK),                                                   \
+      DCHECK_IS_ON() ? (logging::AnalyzerNoReturn(), !(condition)) : false) \
+      << "Check failed: " #condition ". "
+
+#define DPCHECK(condition)                                                  \
+  LAZY_STREAM(                                                              \
+      PLOG_STREAM(DCHECK),                                                  \
+      DCHECK_IS_ON() ? (logging::AnalyzerNoReturn(), !(condition)) : false) \
+      << "Check failed: " #condition ". "
+
+#else
 
 #define DCHECK(condition)                                                \
   LAZY_STREAM(LOG_STREAM(DCHECK), DCHECK_IS_ON() ? !(condition) : false) \
       << "Check failed: " #condition ". "
 
 #define DPCHECK(condition)                                                \
   LAZY_STREAM(PLOG_STREAM(DCHECK), DCHECK_IS_ON() ? !(condition) : false) \
       << "Check failed: " #condition ". "
 
-#endif  // _PREFAST_
+#endif
 
 // Helper macro for binary operators.
 // Don't use this macro directly in your code, use DCHECK_EQ et al below.
 // The 'switch' is used to prevent the 'else' from being ambiguous when the
 // macro is used in an 'if' clause such as:
 // if (a == 1)
 //   DCHECK_EQ(2, a);
 #define DCHECK_OP(name, op, val1, val2)                                \
   switch (0) case 0: default:                                          \
   if (::logging::CheckOpResult true_if_passed =                        \
@@ skipping 268 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_