Add and use SDL_FALLTHROUGH for fallthroughs

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

View file

@ -496,25 +496,13 @@ SDL_FORCE_INLINE void SDL_memset4(void *dst, Uint32 val, size_t dwords)
if (dwords == 0) {
return;
}
/* !!! FIXME: there are better ways to do this, but this is just to clean this up for now. */
#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wimplicit-fallthrough"
#endif
switch (dwords % 4) {
case 0: do { *_p++ = _val; /* fallthrough */
case 3: *_p++ = _val; /* fallthrough */
case 2: *_p++ = _val; /* fallthrough */
case 1: *_p++ = _val; /* fallthrough */
case 0: do { *_p++ = _val; SDL_FALLTHROUGH;
case 3: *_p++ = _val; SDL_FALLTHROUGH;
case 2: *_p++ = _val; SDL_FALLTHROUGH;
case 1: *_p++ = _val;
} while ( --_n );
}
#ifdef __clang__
#pragma clang diagnostic pop
#endif
#endif
}

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 */

View file

@ -1715,7 +1715,7 @@ WaveCheckFormat(WaveFile *file, size_t datalength)
if (file->facthint == FactStrict && file->fact.status <= 0) {
return SDL_SetError("Missing fact chunk in WAVE file");
}
/* fallthrough */
SDL_FALLTHROUGH;
case PCM_CODE:
/* All supported formats require a non-zero bit depth. */
if (file->chunk.size < 16) {
@ -1854,7 +1854,7 @@ WaveLoad(SDL_RWops *src, WaveFile *file, SDL_AudioSpec *spec, Uint8 **audio_buf,
RIFFend = RIFFchunk.position + SDL_MAX_UINT32;
break;
}
/* fallthrough */
SDL_FALLTHROUGH;
case RiffSizeForce:
RIFFend = RIFFchunk.position + RIFFchunk.length;
RIFFlengthknown = SDL_TRUE;

View file

@ -618,10 +618,10 @@ do { \
while (height--) { \
{ int n = (width+3)/4; \
switch (width & 3) { \
case 0: do { op; pixel++; /* fallthrough */ \
case 3: op; pixel++; /* fallthrough */ \
case 2: op; pixel++; /* fallthrough */ \
case 1: op; pixel++; /* fallthrough */ \
case 0: do { op; pixel++; SDL_FALLTHROUGH; \
case 3: op; pixel++; SDL_FALLTHROUGH; \
case 2: op; pixel++; SDL_FALLTHROUGH; \
case 1: op; pixel++; \
} while ( --n > 0 ); \
} \
} \

View file

@ -758,7 +758,7 @@ SDL_iconv(SDL_iconv_t cd,
if (ch > 0x10FFFF) {
ch = UNKNOWN_UNICODE;
}
/* fallthrough */
SDL_FALLTHROUGH;
case ENCODING_UCS4BE:
if (ch > 0x7FFFFFFF) {
ch = UNKNOWN_UNICODE;
@ -780,7 +780,7 @@ SDL_iconv(SDL_iconv_t cd,
if (ch > 0x10FFFF) {
ch = UNKNOWN_UNICODE;
}
/* fallthrough */
SDL_FALLTHROUGH;
case ENCODING_UCS4LE:
if (ch > 0x7FFFFFFF) {
ch = UNKNOWN_UNICODE;

View file

@ -1275,7 +1275,7 @@ SDL_vsscanf(const char *text, const char *fmt, va_list ap)
}
}
}
/* Fall through to %d handling */
SDL_FALLTHROUGH;
case 'd':
if (inttype == DO_LONGLONG) {
Sint64 value;
@ -1323,13 +1323,13 @@ SDL_vsscanf(const char *text, const char *fmt, va_list ap)
if (radix == 10) {
radix = 8;
}
/* Fall through to unsigned handling */
SDL_FALLTHROUGH;
case 'x':
case 'X':
if (radix == 10) {
radix = 16;
}
/* Fall through to unsigned handling */
SDL_FALLTHROUGH;
case 'u':
if (inttype == DO_LONGLONG) {
Uint64 value = 0;
@ -1815,7 +1815,7 @@ SDL_vsnprintf(SDL_OUT_Z_CAP(maxlen) char *text, size_t maxlen, const char *fmt,
case 'p':
case 'x':
info.force_case = SDL_CASE_LOWER;
/* Fall through to 'X' handling */
SDL_FALLTHROUGH;
case 'X':
if (info.force_case == SDL_CASE_NOCHANGE) {
info.force_case = SDL_CASE_UPPER;
@ -1826,12 +1826,12 @@ SDL_vsnprintf(SDL_OUT_Z_CAP(maxlen) char *text, size_t maxlen, const char *fmt,
if (*fmt == 'p') {
inttype = DO_LONG;
}
/* Fall through to unsigned handling */
SDL_FALLTHROUGH;
case 'o':
if (info.radix == 10) {
info.radix = 8;
}
/* Fall through to unsigned handling */
SDL_FALLTHROUGH;
case 'u':
info.force_sign = SDL_FALSE;
if (info.precision >= 0) {

View file

@ -479,14 +479,14 @@ do { \
#define DUFFS_LOOP8(pixel_copy_increment, width) \
{ int n = (width+7)/8; \
switch (width & 7) { \
case 0: do { pixel_copy_increment; /* fallthrough */ \
case 7: pixel_copy_increment; /* fallthrough */ \
case 6: pixel_copy_increment; /* fallthrough */ \
case 5: pixel_copy_increment; /* fallthrough */ \
case 4: pixel_copy_increment; /* fallthrough */ \
case 3: pixel_copy_increment; /* fallthrough */ \
case 2: pixel_copy_increment; /* fallthrough */ \
case 1: pixel_copy_increment; /* fallthrough */ \
case 0: do { pixel_copy_increment; SDL_FALLTHROUGH; \
case 7: pixel_copy_increment; SDL_FALLTHROUGH; \
case 6: pixel_copy_increment; SDL_FALLTHROUGH; \
case 5: pixel_copy_increment; SDL_FALLTHROUGH; \
case 4: pixel_copy_increment; SDL_FALLTHROUGH; \
case 3: pixel_copy_increment; SDL_FALLTHROUGH; \
case 2: pixel_copy_increment; SDL_FALLTHROUGH; \
case 1: pixel_copy_increment; \
} while ( --n > 0 ); \
} \
}
@ -495,10 +495,10 @@ do { \
#define DUFFS_LOOP4(pixel_copy_increment, width) \
{ int n = (width+3)/4; \
switch (width & 3) { \
case 0: do { pixel_copy_increment; /* fallthrough */ \
case 3: pixel_copy_increment; /* fallthrough */ \
case 2: pixel_copy_increment; /* fallthrough */ \
case 1: pixel_copy_increment; /* fallthrough */ \
case 0: do { pixel_copy_increment; SDL_FALLTHROUGH; \
case 3: pixel_copy_increment; SDL_FALLTHROUGH; \
case 2: pixel_copy_increment; SDL_FALLTHROUGH; \
case 1: pixel_copy_increment; \
} while (--n > 0); \
} \
}

View file

@ -145,13 +145,13 @@ SDL_FillRect1(Uint8 * pixels, int pitch, Uint32 color, int w, int h)
switch ((uintptr_t) p & 3) {
case 1:
*p++ = (Uint8) color;
--n; /* fallthrough */
--n; SDL_FALLTHROUGH;
case 2:
*p++ = (Uint8) color;
--n; /* fallthrough */
--n; SDL_FALLTHROUGH;
case 3:
*p++ = (Uint8) color;
--n; /* fallthrough */
--n;
}
SDL_memset4(p, color, (n >> 2));
}
@ -159,11 +159,11 @@ SDL_FillRect1(Uint8 * pixels, int pitch, Uint32 color, int w, int h)
p += (n & ~3);
switch (n & 3) {
case 3:
*p++ = (Uint8) color; /* fallthrough */
*p++ = (Uint8) color; SDL_FALLTHROUGH;
case 2:
*p++ = (Uint8) color; /* fallthrough */
*p++ = (Uint8) color; SDL_FALLTHROUGH;
case 1:
*p++ = (Uint8) color; /* fallthrough */
*p++ = (Uint8) color;
}
}
pixels += pitch;

View file

@ -333,7 +333,7 @@ SDL_MasksToPixelFormatEnum(int bpp, Uint32 Rmask, Uint32 Gmask, Uint32 Bmask,
if (Rmask == 0) {
return SDL_PIXELFORMAT_RGB555;
}
/* fallthrough */
SDL_FALLTHROUGH;
case 16:
if (Rmask == 0) {
return SDL_PIXELFORMAT_RGB565;

View file

@ -323,7 +323,7 @@ DirectFB_WM_ProcessEvent(_THIS, SDL_Window * window, DFBWindowEvent * evt)
}
if (window->flags & SDL_WINDOW_MAXIMIZED)
return 1;
/* fall through */
SDL_FALLTHROUGH;
default:
windata->wm_grab = pos;
if (grabbed_window != NULL)

View file

@ -261,7 +261,7 @@ ProcessWindowEvent(_THIS, SDL_Window *sdlwin, DFBWindowEvent * evt)
SDL_SendWindowEvent(sdlwin, SDL_WINDOWEVENT_MOVED,
evt->x, evt->y);
}
/* fall throught */
SDL_FALLTHROUGH;
case DWET_SIZE:
/* FIXME: what about < 0 */
evt->w -= (windata->theme.right_size + windata->theme.left_size);

View file

@ -729,6 +729,7 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
}
}
/* don't break here, fall through to check the wParam like the button presses */
SDL_FALLTHROUGH;
case WM_LBUTTONUP:
case WM_RBUTTONUP:
case WM_MBUTTONUP:

View file

@ -562,7 +562,7 @@ WatchJoystick(SDL_Joystick * joystick)
if ((event.key.keysym.sym != SDLK_ESCAPE)) {
break;
}
/* Fall through to signal quit */
SDL_FALLTHROUGH;
case SDL_QUIT:
done = SDL_TRUE;
break;
@ -755,7 +755,7 @@ main(int argc, char *argv[])
if ((event.key.keysym.sym != SDLK_ESCAPE)) {
break;
}
/* Fall through to signal quit */
SDL_FALLTHROUGH;
case SDL_QUIT:
done = SDL_TRUE;
break;

View file

@ -386,7 +386,7 @@ loop(void *arg)
if (event.key.keysym.sym != SDLK_ESCAPE) {
break;
}
/* Fall through to signal quit */
SDL_FALLTHROUGH;
case SDL_QUIT:
done = SDL_TRUE;
break;

View file

@ -183,7 +183,7 @@ loop(void *arg)
(event.key.keysym.sym != SDLK_AC_BACK)) {
break;
}
/* Fall through to signal quit */
SDL_FALLTHROUGH;
case SDL_FINGERDOWN:
case SDL_MOUSEBUTTONDOWN:
case SDL_QUIT: