Re: [PATCH 0/2] squelch some "gcc -O3 -Wmaybe-uninitialized" warnings

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> I happened to be compiling git with -O3 today, and noticed we generate
> some warnings about uninitialized variables (I actually compile with
> -Wall, but the only false positives I saw were these).
>
> Here are patches to squelch them.
>
>   [1/2]: error_errno: use constant return similar to error()
>   [2/2]: color_parse_mem: initialize "struct color" temporary

Interesting.  Here is for "gcc -Os" on top to appease gcc 4.8.4 that
I probably am NOT going to apply.  These are all false positives.

The ones on config.c is the most curious as these two "ret" needs a
false initialization, but the one that comes after them
git_config_ulong() that has the same code structure does not get any
warning, which made absolutely no sense to me.


 builtin/update-index.c | 2 +-
 config.c               | 4 ++--
 diff.c                 | 2 +-
 fast-import.c          | 1 +
 4 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/builtin/update-index.c b/builtin/update-index.c
index ba04b19..a202612 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -832,7 +832,7 @@ static int cacheinfo_callback(struct parse_opt_ctx_t *ctx,
 				const struct option *opt, int unset)
 {
 	unsigned char sha1[20];
-	unsigned int mode;
+	unsigned int mode = 0;
 	const char *path;
 
 	if (!parse_new_style_cacheinfo(ctx->argv[1], &mode, sha1, &path)) {
diff --git a/config.c b/config.c
index 0dfed68..52133aa 100644
--- a/config.c
+++ b/config.c
@@ -685,7 +685,7 @@ static void die_bad_number(const char *name, const char *value)
 
 int git_config_int(const char *name, const char *value)
 {
-	int ret;
+	int ret = 0;
 	if (!git_parse_int(value, &ret))
 		die_bad_number(name, value);
 	return ret;
@@ -693,7 +693,7 @@ int git_config_int(const char *name, const char *value)
 
 int64_t git_config_int64(const char *name, const char *value)
 {
-	int64_t ret;
+	int64_t ret = 0;
 	if (!git_parse_int64(value, &ret))
 		die_bad_number(name, value);
 	return ret;
diff --git a/diff.c b/diff.c
index c7e2605..1098198 100644
--- a/diff.c
+++ b/diff.c
@@ -995,7 +995,7 @@ static int find_word_boundaries(mmfile_t *buffer, regex_t *word_regex,
 static void diff_words_fill(struct diff_words_buffer *buffer, mmfile_t *out,
 		regex_t *word_regex)
 {
-	int i, j;
+	int i, j = 0;
 	long alloc = 0;
 
 	out->size = 0;
diff --git a/fast-import.c b/fast-import.c
index bf53ac9..abc4519 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1377,6 +1377,7 @@ static const char *get_mode(const char *str, uint16_t *modep)
 	unsigned char c;
 	uint16_t mode = 0;
 
+	*modep = 0;
 	while ((c = *str++) != ' ') {
 		if (c < '0' || c > '7')
 			return NULL;