Commit a48eafa7 authored by Simon McVittie's avatar Simon McVittie

utils: Add fallback definitions for alignof, offsetof, static_assert

This assumes either a C11 compiler, or as a fallback, a tolerably new
version of gcc.
Signed-off-by: Simon McVittie's avatarSimon McVittie <>
parent fc9c12ed
......@@ -56,6 +56,7 @@ WARN_CFLAGS=$(echo "$WARN_CFLAGS" | sed -Ee 's,-W(error=)?declaration-after-stat
WARN_CFLAGS=$(echo "$WARN_CFLAGS" | sed -Ee 's,-W(error=)?pointer-arith,,')
AM_CONDITIONAL([ENABLE_SHARED], [test "x$enable_shared" = xyes])
// Copyright © 2017 Collabora Ltd
// Copyright © 2017-2020 Collabora Ltd
// This file is part of libcapsule.
......@@ -17,6 +17,7 @@
#pragma once
#include <assert.h>
#include <limits.h>
#include <stdarg.h>
#include <stddef.h>
......@@ -26,6 +27,10 @@
#include "debug.h"
#include <stdalign.h>
#define UNLIKELY(x) __builtin_expect(x, 0)
#define LIKELY(x) __builtin_expect(x, 1)
......@@ -187,3 +192,40 @@ _capsule_clear( void *pp )
* on exit from its scope.
#define _capsule_autofree _capsule_cleanup(_capsule_clear)
* alignof:
* @type: A type
* The same as in Standard C: return the minimal alignment of a type.
* Note that this is not the same as gcc __alignof__, which returns the
* type's *preferred* alignment, which is sometimes greater than the
* *minimal* alignment returned by this macro.
#ifndef alignof
# define alignof(type) (__builtin_offsetof(struct { char a; type b; }, b))
* offsetof:
* @t: A `struct` type
* @m: A member
* The same as in Standard C: return the offset of @m within @t.
#ifndef offsetof
# define offsetof(t, m) (__builtin_offsetof(t, m))
* static_assert:
* @expr: An expression to evaluate at compile-time
* @message: A diagnostic message used if @expr is not true
* The same as in Standard C: evaluate @expr as a compile-time constant
* expression, and fail to build if it is zero.
#ifndef static_assert
# define static_assert(expr, message) _Static_assert(expr, message)
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