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-rw-r--r--third_party/base/compiler_specific.h56
1 files changed, 27 insertions, 29 deletions
diff --git a/third_party/base/compiler_specific.h b/third_party/base/compiler_specific.h
index 3dbd1abb33..57f7a93e59 100644
--- a/third_party/base/compiler_specific.h
+++ b/third_party/base/compiler_specific.h
@@ -43,22 +43,6 @@
#define MSVC_DISABLE_OPTIMIZE() __pragma(optimize("", off))
#define MSVC_ENABLE_OPTIMIZE() __pragma(optimize("", on))
-// Allows exporting a class that inherits from a non-exported base class.
-// This uses suppress instead of push/pop because the delimiter after the
-// declaration (either "," or "{") has to be placed before the pop macro.
-//
-// Example usage:
-// class EXPORT_API Foo : NON_EXPORTED_BASE(public Bar) {
-//
-// MSVC Compiler warning C4275:
-// non dll-interface class 'Bar' used as base for dll-interface class 'Foo'.
-// Note that this is intended to be used only when no access to the base class'
-// static data is done through derived classes or inline methods. For more info,
-// see http://msdn.microsoft.com/en-us/library/3tdb471s(VS.80).aspx
-#define NON_EXPORTED_BASE(code) \
- MSVC_SUPPRESS_WARNING(4275) \
- code
-
#else // Not MSVC
#define _Printf_format_string_
@@ -68,7 +52,6 @@
#define MSVC_POP_WARNING()
#define MSVC_DISABLE_OPTIMIZE()
#define MSVC_ENABLE_OPTIMIZE()
-#define NON_EXPORTED_BASE(code) code
#endif // COMPILER_MSVC
@@ -78,7 +61,7 @@
// Use like:
// int x = ...;
// ALLOW_UNUSED_LOCAL(x);
-#define ALLOW_UNUSED_LOCAL(x) false ? (void)x : (void)0
+#define ALLOW_UNUSED_LOCAL(x) (void)x
// Annotate a typedef or function indicating it's ok if it's not used.
// Use like:
@@ -112,21 +95,29 @@
// Use like:
// class ALIGNAS(16) MyClass { ... }
// ALIGNAS(16) int array[4];
+//
+// In most places you can use the C++11 keyword "alignas", which is preferred.
+//
+// But compilers have trouble mixing __attribute__((...)) syntax with
+// alignas(...) syntax.
+//
+// Doesn't work in clang or gcc:
+// struct alignas(16) __attribute__((packed)) S { char c; };
+// Works in clang but not gcc:
+// struct __attribute__((packed)) alignas(16) S2 { char c; };
+// Works in clang and gcc:
+// struct alignas(16) S3 { char c; } __attribute__((packed));
+//
+// There are also some attributes that must be specified *before* a class
+// definition: visibility (used for exporting functions/classes) is one of
+// these attributes. This means that it is not possible to use alignas() with a
+// class that is marked as exported.
#if defined(COMPILER_MSVC)
#define ALIGNAS(byte_alignment) __declspec(align(byte_alignment))
#elif defined(COMPILER_GCC)
#define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment)))
#endif
-// Return the byte alignment of the given type (available at compile time).
-// Use like:
-// ALIGNOF(int32_t) // this would be 4
-#if defined(COMPILER_MSVC)
-#define ALIGNOF(type) __alignof(type)
-#elif defined(COMPILER_GCC)
-#define ALIGNOF(type) __alignof__(type)
-#endif
-
// Annotate a function indicating the caller must examine the return value.
// Use like:
// int foo() WARN_UNUSED_RESULT;
@@ -207,7 +198,7 @@
// Macro for hinting that an expression is likely to be false.
#if !defined(UNLIKELY)
-#if defined(COMPILER_GCC)
+#if defined(COMPILER_GCC) || defined(__clang__)
#define UNLIKELY(x) __builtin_expect(!!(x), 0)
#else
#define UNLIKELY(x) (x)
@@ -215,7 +206,7 @@
#endif // !defined(UNLIKELY)
#if !defined(LIKELY)
-#if defined(COMPILER_GCC)
+#if defined(COMPILER_GCC) || defined(__clang__)
#define LIKELY(x) __builtin_expect(!!(x), 1)
#else
#define LIKELY(x) (x)
@@ -230,4 +221,11 @@
#define HAS_FEATURE(FEATURE) 0
#endif
+// Macro for telling -Wimplicit-fallthrough that a fallthrough is intentional.
+#if defined(__clang__)
+#define FALLTHROUGH [[clang::fallthrough]]
+#else
+#define FALLTHROUGH
+#endif
+
#endif // BASE_COMPILER_SPECIFIC_H_