Merge "Declare __fake_use_va_args as a constexpr function."

/*

 * Use __VA_ARGS__ if running a static analyzer,

 * to avoid warnings of unused variables in __VA_ARGS__.

 * __FAKE_USE_VA_ARGS is undefined at link time,

 * so don't link with __clang_analyzer__ defined.

 * Use contexpr function in C++ mode, so these macros can be used

 * in other constexpr functions without warning.

 */

#ifdef __clang_analyzer__

extern void __fake_use_va_args(int, ...);

#define __FAKE_USE_VA_ARGS(...) __fake_use_va_args(0, ##__VA_ARGS__)

#ifdef __cplusplus

extern "C++" {

template <typename... Ts>

constexpr int __fake_use_va_args(Ts...) {

  return 0;

}

}

#else

extern int __fake_use_va_args(int, ...);

#endif /* __cplusplus */

#define __FAKE_USE_VA_ARGS(...) ((void)__fake_use_va_args(0, ##__VA_ARGS__))

#else

#define __FAKE_USE_VA_ARGS(...) ((void)(0))

#endif

#endif /* __clang_analyzer__ */

#ifndef __predict_false

#define __predict_false(exp) __builtin_expect((exp) != 0, 0)