base/compiler_specific.h

// Copyright 2008 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 MINI_CHROMIUM_BASE_COMPILER_SPECIFIC_H_
#define MINI_CHROMIUM_BASE_COMPILER_SPECIFIC_H_

#include "build/build_config.h"

#if defined(COMPILER_MSVC)

// MSVC_SUPPRESS_WARNING disables warning |n| for the remainder of the line and
// for the next line of the source file.
#define MSVC_SUPPRESS_WARNING(n) __pragma(warning(suppress:n))

// MSVC_PUSH_DISABLE_WARNING pushes |n| onto a stack of warnings to be disabled.
// The warning remains disabled until popped by MSVC_POP_WARNING.
#define MSVC_PUSH_DISABLE_WARNING(n) __pragma(warning(push)) \
                                     __pragma(warning(disable:n))

// Pop effects of innermost MSVC_PUSH_* macro.
#define MSVC_POP_WARNING() __pragma(warning(pop))

#else  // Not MSVC

#define MSVC_SUPPRESS_WARNING(n)
#define MSVC_PUSH_DISABLE_WARNING(n)
#define MSVC_POP_WARNING()

#endif  // COMPILER_MSVC

// Annotate a variable indicating it's ok if the variable is not used.
// (Typically used to silence a compiler warning when the assignment
// is important for some other reason.)
// Use like:
//   int x = ...;
//   ALLOW_UNUSED_LOCAL(x);
#define ALLOW_UNUSED_LOCAL(x) false ? (void)x : (void)0

// Annotate a typedef or function indicating it's ok if it's not used.
// Use like:
//   typedef Foo Bar ALLOW_UNUSED_TYPE;
#if defined(COMPILER_GCC)
#define ALLOW_UNUSED_TYPE __attribute__((unused))
#else
#define ALLOW_UNUSED_TYPE
#endif

// Specify memory alignment for structs, classes, etc.
// Use like:
//   class ALIGNAS(16) MyClass { ... }
//   ALIGNAS(16) int array[4];
#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

#if defined(COMPILER_MSVC)
#define WARN_UNUSED_RESULT
#else
#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
#endif

#if defined(COMPILER_MSVC)
#define PRINTF_FORMAT(format_param, dots_param)
#else
#define PRINTF_FORMAT(format_param, dots_param) \
    __attribute__((format(printf, format_param, dots_param)))
#endif

// Compiler feature-detection.
// clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension
#if defined(__has_feature)
#define HAS_FEATURE(FEATURE) __has_feature(FEATURE)
#else
#define HAS_FEATURE(FEATURE) 0
#endif

// Macro for telling -Wimplicit-fallthrough that a fallthrough is intentional.
#if __cplusplus >= 201703L  // C++17
#define FALLTHROUGH [[fallthrough]]
#elif defined(__clang__)
#define FALLTHROUGH [[clang::fallthrough]]
#else
#define FALLTHROUGH
#endif

#endif  // MINI_CHROMIUM_BASE_COMPILER_SPECIFIC_H_