[PATCH v2 2/4] do full type check in BARF_UNLESS_COPYABLE
- From
René Scharfe <l.s.r@web.de>
- Date
- Jan 1, 2023, 21:11 UTC
- Message-ID
- <4f161041-b299-f79a-e01b-cc00e2880850@web.de>
- In-Reply-To
- <9bc1bd74-f72c-1b43-df7c-950815babb03@web.de>
Use __builtin_types_compatible_p to perform a full type check if possible. Otherwise fall back to the old size comparison, but add a non-evaluated assignment to catch more type mismatches. It doesn't flag copies between arrays with different signedness, but that's as close to a full type check as it gets without the builtin, as far as I can see.
Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: René Scharfe <l.s.r@web.de> --- git-compat-util.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/git-compat-util.h b/git-compat-util.h index 940d03150c..e81bb14fc9 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -97,8 +97,14 @@ struct strbuf; # define BARF_UNLESS_AN_ARRAY(arr) \ BUILD_ASSERT_OR_ZERO(!__builtin_types_compatible_p(__typeof__(arr), \ __typeof__(&(arr)[0]))) +# define BARF_UNLESS_COPYABLE(dst, src) \ + BUILD_ASSERT_OR_ZERO(__builtin_types_compatible_p(__typeof__(*(dst)), \ + __typeof__(*(src)))) #else # define BARF_UNLESS_AN_ARRAY(arr) 0 +# define BARF_UNLESS_COPYABLE(dst, src) \ + BUILD_ASSERT_OR_ZERO(0 ? ((*(dst) = *(src)), 0) : \ + sizeof(*(dst)) == sizeof(*(src))) #endif /* * ARRAY_SIZE - get the number of elements in a visible array @@ -1093,9 +1099,6 @@ int xstrncmpz(const char *s, const char *t, size_t len); #define CALLOC_ARRAY(x, alloc) (x) = xcalloc((alloc), sizeof(*(x))) #define REALLOC_ARRAY(x, alloc) (x) = xrealloc((x), st_mult(sizeof(*(x)), (alloc))) -#define BARF_UNLESS_COPYABLE(dst, src) \ - BUILD_ASSERT_OR_ZERO(sizeof(*(dst)) == sizeof(*(src))) - #define COPY_ARRAY(dst, src, n) copy_array((dst), (src), (n), sizeof(*(dst)) + \ BARF_UNLESS_COPYABLE((dst), (src))) static inline void copy_array(void *dst, const void *src, size_t n, size_t size) -- 2.39.0