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.
5 #ifndef MOJO_PUBLIC_C_SYSTEM_MACROS_H_
6 #define MOJO_PUBLIC_C_SYSTEM_MACROS_H_
10 // Annotate a variable indicating it's okay if it's unused.
12 // int x MOJO_ALLOW_UNUSED = ...;
14 #define MOJO_ALLOW_UNUSED __attribute__((unused))
16 #define MOJO_ALLOW_UNUSED
19 // Annotate a function indicating that the caller must examine the return value.
21 // int foo() MOJO_WARN_UNUSED_RESULT;
22 // Note that it can only be used on the prototype, and not the definition.
24 #define MOJO_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
26 #define MOJO_WARN_UNUSED_RESULT
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.
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]
40 #define MOJO_COMPILE_ASSERT(expr, msg)
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))
53 #error "Please define MOJO_ALIGNOF() for your compiler."
56 // Specify the alignment of a |struct|, etc.
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))
69 #error "Please define MOJO_ALIGNAS() for your compiler."
72 #endif // MOJO_PUBLIC_C_SYSTEM_MACROS_H_