eden-emu/SDL
15
0
Fork 0
mirror of https://github.com/libsdl-org/SDL.git synced 2025-05-18 18:58:27 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Add and use SDL_FALLTHROUGH for fallthroughs

Browse source 
Case fallthrough warnings can be suppressed using the __fallthrough__
compiler attribute. Unfortunately, not all compilers have this
attribute, or even have __has_attribute to check if they have the
__fallthrough__ attribute. [[fallthrough]] is also available in C++17
and the next C2x, but not everyone uses C++17 or C2x.

So define the SDL_FALLTHROUGH macro to deal with those problems - if we
are using C++17 or C2x, it expands to [[fallthrough]]; else if the
compiler has __has_attribute and has the __fallthrough__ attribute, then
it expands to __attribute__((__fallthrough__)); else it expands to an
empty statement, with a /* fallthrough */ comment (it's a do {} while
(0) statement, because users of this macro need to use a semicolon,
because [[fallthrough]] and __attribute__((__fallthrough__)) require a
semicolon).

Applications using SDL are also free to use this macro (because it is
defined in begin_code.h).

All existing /* fallthrough */ comments have been replaced with this
macro. Some of them were unnecessary because they were the last case in
a switch; using SDL_FALLTHROUGH in those cases would result in a compile
error on compilers that support __fallthrough__, for having a
__attribute__((__fallthrough__)) statement that didn't immediately
precede a case label.
This commit is contained in:
Misa 2021-09-27 14:38:12 -07:00 • committed by Sam Lantinga
parent 828a0a4a10
commit 66a08aa391
15 changed files with 63 additions and 55 deletions
Download patch file Download diff file Expand all files Collapse all files

19
include/begin_code.h
View file

@ -164,3 +164,22 @@
#endif
#endif /* NULL */
#endif /* ! Mac OS X - breaks precompiled headers */
#ifndef SDL_FALLTHROUGH
#if (defined(__cplusplus) && __cplusplus >= 201703L) || \
(defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202000L)
#define SDL_FALLTHROUGH [[fallthrough]]
#else
#ifdef __has_attribute
#define _HAS_FALLTHROUGH __has_attribute(__fallthrough__)
#else
#define _HAS_FALLTHROUGH 0
#endif /* __has_attribute */
#if _HAS_FALLTHROUGH
#define SDL_FALLTHROUGH __attribute__((__fallthrough__))
#else
#define SDL_FALLTHROUGH do {} while (0) /* fallthrough */
#endif /* _HAS_FALLTHROUGH */
#undef _HAS_FALLTHROUGH
#endif /* C++17 or C2x */
#endif /* SDL_FALLTHROUGH not defined */