1 files changed, 56 insertions, 0 deletions
diff --git a/internal/base/macros.h b/internal/base/macros.h
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+++ b/internal/base/macros.h
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+// This code is compiled directly on many platforms, including client
+// platforms like Windows, Mac, and embedded systems.  Before making
+// any changes here, make sure that you're not breaking any platforms.
+//
+
+#ifndef DYNAMIC_DEPTH_INTERNAL_BASE_MACROS_H_  // NOLINT
+#define DYNAMIC_DEPTH_INTERNAL_BASE_MACROS_H_  // NOLINT
+
+#include <stddef.h>  // For size_t
+#include "base/port.h"
+
+// The FALLTHROUGH_INTENDED macro can be used to annotate implicit fall-through
+// between switch labels:
+//  switch (x) {
+//    case 40:
+//    case 41:
+//      if (truth_is_out_there) {
+//        ++x;
+//        FALLTHROUGH_INTENDED;  // Use instead of/along with annotations in
+//                               // comments.
+//      } else {
+//        return x;
+//      }
+//    case 42:
+//      ...
+//
+//  As shown in the example above, the FALLTHROUGH_INTENDED macro should be
+//  followed by a semicolon. It is designed to mimic control-flow statements
+//  like 'break;', so it can be placed in most places where 'break;' can, but
+//  only if there are no statements on the execution path between it and the
+//  next switch label.
+//
+//  When compiled with clang in C++11 mode, the FALLTHROUGH_INTENDED macro is
+//  expanded to [[clang::fallthrough]] attribute, which is analysed when
+//  performing switch labels fall-through diagnostic ('-Wimplicit-fallthrough').
+//  See clang documentation on language extensions for details:
+//  http://clang.llvm.org/docs/AttributeReference.html#fallthrough-clang-fallthrough
+//
+//  When used with unsupported compilers, the FALLTHROUGH_INTENDED macro has no
+//  effect on diagnostics.
+//
+//  In either case this macro has no effect on runtime behavior and performance
+//  of code.
+#if defined(__clang__) && defined(LANG_CXX11) && defined(__has_warning)
+#if __has_feature(cxx_attributes) && __has_warning("-Wimplicit-fallthrough")
+#define FALLTHROUGH_INTENDED [[clang::fallthrough]]  // NOLINT
+#endif
+#endif
+
+#ifndef FALLTHROUGH_INTENDED  // NOLINT
+#define FALLTHROUGH_INTENDED \
+  do {                       \
+  } while (0)
+#endif
+
+#endif // DYNAMIC_DEPTH_INTERNAL_BASE_MACROS_H_  // NOLINT