mirror of
https://github.com/klzgrad/naiveproxy.git
synced 2024-12-01 01:36:09 +03:00
48 lines
1.7 KiB
C
48 lines
1.7 KiB
C
// Copyright 2015 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 BUILD_BUILDFLAG_H_
|
|
#define BUILD_BUILDFLAG_H_
|
|
|
|
// These macros un-mangle the names of the build flags in a way that looks
|
|
// natural, and gives errors if the flag is not defined. Normally in the
|
|
// preprocessor it's easy to make mistakes that interpret "you haven't done
|
|
// the setup to know what the flag is" as "flag is off". Normally you would
|
|
// include the generated header rather than include this file directly.
|
|
//
|
|
// This is for use with generated headers. See build/buildflag_header.gni.
|
|
|
|
// This dance of two macros does a concatenation of two preprocessor args using
|
|
// ## doubly indirectly because using ## directly prevents macros in that
|
|
// parameter from being expanded.
|
|
#define BUILDFLAG_CAT_INDIRECT(a, b) a ## b
|
|
#define BUILDFLAG_CAT(a, b) BUILDFLAG_CAT_INDIRECT(a, b)
|
|
|
|
// Accessor for build flags.
|
|
//
|
|
// To test for a value, if the build file specifies:
|
|
//
|
|
// ENABLE_FOO=true
|
|
//
|
|
// Then you would check at build-time in source code with:
|
|
//
|
|
// #include "foo_flags.h" // The header the build file specified.
|
|
//
|
|
// #if BUILDFLAG(ENABLE_FOO)
|
|
// ...
|
|
// #endif
|
|
//
|
|
// There will no #define called ENABLE_FOO so if you accidentally test for
|
|
// whether that is defined, it will always be negative. You can also use
|
|
// the value in expressions:
|
|
//
|
|
// const char kSpamServerName[] = BUILDFLAG(SPAM_SERVER_NAME);
|
|
//
|
|
// Because the flag is accessed as a preprocessor macro with (), an error
|
|
// will be thrown if the proper header defining the internal flag value has
|
|
// not been included.
|
|
#define BUILDFLAG(flag) (BUILDFLAG_CAT(BUILDFLAG_INTERNAL_, flag)())
|
|
|
|
#endif // BUILD_BUILDFLAG_H_
|