csum-file: fix -Wsign-compare warning on 32-bit platform

On 32-bit platforms, ssize_t may be "int" while size_t may be
"unsigned int".  At times we compare the number of bytes we read
stored in a ssize_t variable with "unsigned int", but that is done
after we check that we did not get an error return (which is
negative---and that is the whole reason why we used ssize_t and not
size_t), so these comparisons are safe.

But compilers may not realize that.  Cast these to size_t to work
around the false positives.  On platforms with size_t/ssize_t wider
than a normal int, this won't be an issue.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: gitster

csum-file.c

@@ -9,7 +9,6 @@
  */
 
 #define USE_THE_REPOSITORY_VARIABLE
-#define DISABLE_SIGN_COMPARE_WARNINGS
 
 #include "git-compat-util.h"
 #include "progress.h"
@@ -24,7 +23,7 @@ static void verify_buffer_or_die(struct hashfile *f,
 
 	if (ret < 0)
 		die_errno("%s: sha1 file read error", f->name);
-	if (ret != count)
+	if ((size_t)ret != count)
 		die("%s: sha1 file truncated", f->name);
 	if (memcmp(buf, f->check_buffer, count))
 		die("sha1 file '%s' validation error", f->name);