>
> This commit adds a SPICE_UNREACHABLE macro (courtesy of Frediano)
> so that gcc does not think that code control can go past
> spice_return_{val_,}if_fail(), spice_critical() and spice_error()
>
> This avoids this kind of warnings:
>
> fallthrough.c:
>
> #include "log.h"
>
> int main(int argc, char **argv)
> {
> switch(argc) {
> case 1:
> spice_critical("foo");
> default:
> return 0;
> }
> }
>
> $ gcc -c $(pkg-config --cflags --libs glib-2.0 spice-protocol)
> -I common -Wimplicit-fallthrough=5 ./fallthrough.c
> In file included from ./fallthrough.c:1:
> ./fallthrough.c: In function 'main':
> common/log.h:73:5: warning: this statement may fall through
> [-Wimplicit-fallthrough=]
> 73 | spice_log(G_LOG_LEVEL_CRITICAL, SPICE_STRLOC, __FUNCTION__, ""
> format, ## __VA_ARGS__); \
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ./fallthrough.c:8:25: note: in expansion of macro 'spice_critical'
> 8 | spice_critical("foo");
> | ^~~~~~~~~~~~~~
> ./fallthrough.c:9:17: note: here
> 9 | default:
> | ^~~~~~~
>
> Signed-off-by: Christophe Fergeau <cfergeau@xxxxxxxxxx>
> ---
> Maybe a bit too much for a single commit, I can split :)
>
Acked-by: Frediano Ziglio <fziglio@xxxxxxxxxx>
> common/log.h | 8 ++++++--
> common/macros.h | 8 ++++++++
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/common/log.h b/common/log.h
> index 7c67e7a..201c87a 100644
> --- a/common/log.h
> +++ b/common/log.h
> @@ -39,16 +39,18 @@ void spice_log(GLogLevelFlags log_level,
> const char *format,
> ...) G_GNUC_PRINTF(4, 5);
>
> +/* FIXME: name is misleading, this aborts.. */
> #define spice_return_if_fail(x) G_STMT_START { \
> if G_LIKELY(x) { } else { \
> - spice_log(G_LOG_LEVEL_CRITICAL, SPICE_STRLOC, G_STRFUNC, "condition
> `%s' failed", #x); \
> + spice_critical("condition `%s' failed", #x); \
> return; \
> } \
> } G_STMT_END
>
> +/* FIXME: name is misleading, this aborts.. */
> #define spice_return_val_if_fail(x, val) G_STMT_START { \
> if G_LIKELY(x) { } else { \
> - spice_log(G_LOG_LEVEL_CRITICAL, SPICE_STRLOC, __FUNCTION__,
> "condition `%s' failed", #x); \
> + spice_critical("condition `%s' failed", #x); \
> return (val); \
> } \
> } G_STMT_END
> @@ -71,10 +73,12 @@ void spice_log(GLogLevelFlags log_level,
>
> #define spice_critical(format, ...) G_STMT_START {
> \
> spice_log(G_LOG_LEVEL_CRITICAL, SPICE_STRLOC, __FUNCTION__, "" format,
> ## __VA_ARGS__); \
> + SPICE_UNREACHABLE;
> \
> } G_STMT_END
>
> #define spice_error(format, ...) G_STMT_START { \
> spice_log(G_LOG_LEVEL_ERROR, SPICE_STRLOC, __FUNCTION__, "" format, ##
> __VA_ARGS__); \
> + SPICE_UNREACHABLE;
> \
> } G_STMT_END
>
> #define spice_warn_if_fail(x) G_STMT_START { \
> diff --git a/common/macros.h b/common/macros.h
> index 2f24ada..92cd82c 100644
> --- a/common/macros.h
> +++ b/common/macros.h
> @@ -55,4 +55,12 @@
>
> #define SPICE_VERIFY(cond) verify_expr(cond, (void)1)
>
> +#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
> +#define SPICE_UNREACHABLE __builtin_unreachable()
> +#elif defined(_MSC_VER)
> +#define SPICE_UNREACHABLE __assume(0)
> +#else
> +#define SPICE_UNREACHABLE for(;;) continue
> +#endif
> +
> #endif // H_SPICE_COMMON_MACROS
Frediano
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