linux_kernel/include/linux/compiler-clang.h

#ifndef __LINUX_COMPILER_H
#error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead."
#endif

/* Some compiler specific definitions are overwritten here
 * for Clang compiler
 */

#ifdef uninitialized_var
#undef uninitialized_var
#define uninitialized_var(x) x = *(&(x))
#endif

/* same as gcc, this was present in clang-2.6 so we can assume it works
 * with any version that can compile the kernel
 */
#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)

/*
 * GCC does not warn about unused static inline functions for
 * -Wunused-function.  This turns out to avoid the need for complex #ifdef
 * directives.  Suppress the warning in clang as well.
 */
#undef inline
#define inline inline __attribute__((unused)) notrace