Junio C Hamano <gitster@xxxxxxxxx> writes:
> pack-mtimes.c: In function ‘load_pack_mtimes_file’:
> Error: pack-mtimes.c:89:25: ‘mtimes_size’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 89 | munmap(data, mtimes_size);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> make: *** [Makefile:2757: pack-mtimes.o] Error 1
> make: *** Waiting for unfinished jobs....
The use on line 89 is guarded with "if (data)" and data can become
non-NULL only after mtimes_size is computed, so this is benign.
They have excuse for a false positive because the warning is about
"maybe" uninitialized, but that does not help our annoyance factor
X-<.
> pack-revindex.c: In function ‘load_revindex_from_disk’:
> Error: pack-revindex.c:260:25: ‘revindex_size’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 260 | munmap(data, revindex_size);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> make: *** [Makefile:2757: pack-revindex.o] Error 1
> cat: exit.status: No such file or directory
This follows exactly the same pattern established by the other one
(or perhaps the other one copied from here). It is another false
positive.
I am not sure what the right fix would be. For example, if we were
interested in avoiding to incur too much resources for revindex, we
might do something like this
--- i/pack-revindex.c
+++ w/pack-revindex.c
@@ -258,6 +258,8 @@ static int load_revindex_from_disk(char *revindex_name,
if (ret) {
if (data)
munmap(data, revindex_size);
+ fprintf(stderr, "would have fit %d revindex in 10MB\n",
+ 10 * 1024 * 1024 / revindex_size);
} else {
*len_p = revindex_size;
*data_p = (const uint32_t *)data;
without even guarding with "if (data)".
If we "initialize" revindex_size to a meaningless dummy value like 0
like the attached would _hide_ such a real bug from the compiler, so
I dunno.
@@ -206,7 +206,7 @@ static int load_revindex_from_disk(char *revindex_name,
int fd, ret = 0;
struct stat st;
void *data = NULL;
- size_t revindex_size;
+ size_t revindex_size = 0;
struct revindex_header *hdr;
if (git_env_bool(GIT_TEST_REV_INDEX_DIE_ON_DISK, 0))
