1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef MOJO_PUBLIC_C_SYSTEM_MACROS_H_ 6 #define MOJO_PUBLIC_C_SYSTEM_MACROS_H_ 7 8 #include <stddef.h> 9 10 // Annotate a variable indicating it's okay if it's unused. 11 // Use like: 12 // int x MOJO_ALLOW_UNUSED = ...; 13 #if defined(__GNUC__) 14 #define MOJO_ALLOW_UNUSED __attribute__((unused)) 15 #else 16 #define MOJO_ALLOW_UNUSED 17 #endif 18 19 // Annotate a function indicating that the caller must examine the return value. 20 // Use like: 21 // int foo() MOJO_WARN_UNUSED_RESULT; 22 // Note that it can only be used on the prototype, and not the definition. 23 #if defined(__GNUC__) 24 #define MOJO_WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 25 #else 26 #define MOJO_WARN_UNUSED_RESULT 27 #endif 28 29 // Assert things at compile time. (|msg| should be a valid identifier name.) 30 // This macro is currently C++-only, but we want to use it in the C core.h. 31 // Use like: 32 // MOJO_COMPILE_ASSERT(sizeof(Foo) == 12, Foo_has_invalid_size); 33 #if __cplusplus >= 201103L 34 #define MOJO_COMPILE_ASSERT(expr, msg) static_assert(expr, #msg) 35 #elif defined(__cplusplus) 36 namespace mojo { template <bool> struct CompileAssert {}; } 37 #define MOJO_COMPILE_ASSERT(expr, msg) \ 38 typedef ::mojo::CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1] 39 #else 40 #define MOJO_COMPILE_ASSERT(expr, msg) 41 #endif 42 43 // Like the C++11 |alignof| operator. 44 #if __cplusplus >= 201103L 45 #define MOJO_ALIGNOF(type) alignof(type) 46 #elif defined(__GNUC__) 47 #define MOJO_ALIGNOF(type) __alignof__(type) 48 #elif defined(_MSC_VER) 49 // The use of |sizeof| is to work around a bug in MSVC 2010 (see 50 // http://goo.gl/isH0C; supposedly fixed since then). 51 #define MOJO_ALIGNOF(type) (sizeof(type) - sizeof(type) + __alignof(type)) 52 #else 53 #error "Please define MOJO_ALIGNOF() for your compiler." 54 #endif 55 56 // Specify the alignment of a |struct|, etc. 57 // Use like: 58 // struct MOJO_ALIGNAS(8) Foo { ... }; 59 // Unlike the C++11 |alignas()|, |alignment| must be an integer. It may not be a 60 // type, nor can it be an expression like |MOJO_ALIGNOF(type)| (due to the 61 // non-C++11 MSVS version). 62 #if __cplusplus >= 201103L 63 #define MOJO_ALIGNAS(alignment) alignas(alignment) 64 #elif defined(__GNUC__) 65 #define MOJO_ALIGNAS(alignment) __attribute__((aligned(alignment))) 66 #elif defined(_MSC_VER) 67 #define MOJO_ALIGNAS(alignment) __declspec(align(alignment)) 68 #else 69 #error "Please define MOJO_ALIGNAS() for your compiler." 70 #endif 71 72 #endif // MOJO_PUBLIC_C_SYSTEM_MACROS_H_ 73
