From c112084af965ade0836b7c226c68ecd8b536fc0a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ren=C3=A9=20Scharfe?= Date: Wed, 9 May 2018 23:06:46 +0200 Subject: fast-export: avoid NULL pointer arithmetic Clang 6 reports the following warning, which is turned into an error in a DEVELOPER build: builtin/fast-export.c:162:28: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic] return ((uint32_t *)NULL) + mark; ~~~~~~~~~~~~~~~~~~ ^ 1 error generated. The compiler is correct, and the error message speaks for itself. There is no need for any undefined operation -- just cast mark to void * or uint32_t after an intermediate cast to uintptr_t. That encodes the integer value into a pointer and later decodes it as intended. While at it remove an outdated comment -- intptr_t has been used since ffe659f94d (parse-options: make some arguments optional, add callbacks), committed in October 2007. Signed-off-by: Rene Scharfe Acked-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- builtin/fast-export.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/builtin/fast-export.c b/builtin/fast-export.c index c0652a7ed0..9aa4f7fce8 100644 --- a/builtin/fast-export.c +++ b/builtin/fast-export.c @@ -154,15 +154,14 @@ static void anonymize_path(struct strbuf *out, const char *path, } } -/* Since intptr_t is C99, we do not use it here */ -static inline uint32_t *mark_to_ptr(uint32_t mark) +static inline void *mark_to_ptr(uint32_t mark) { - return ((uint32_t *)NULL) + mark; + return (void *)(uintptr_t)mark; } static inline uint32_t ptr_to_mark(void * mark) { - return (uint32_t *)mark - (uint32_t *)NULL; + return (uint32_t)(uintptr_t)mark; } static inline void mark_object(struct object *object, uint32_t mark) -- cgit v1.2.3