[PATCH] Remove unused assignments

[PATCH] Remove unused assignments

[Benjamin Kramer]

These variables were always overwritten or the assigned
value was unused:

builtin-diff-tree.c::cmd_diff_tree(): nr_sha1
builtin-for-each-ref.c::opt_parse_sort(): sort_tail
builtin-mailinfo.c::decode_header_bq(): in
builtin-shortlog.c::insert_one_record(): len
connect.c::git_connect(): path
imap-send.c::v_issue_imap_cmd(): n
pretty.c::pp_user_info(): filler
remote::parse_refspec_internal(): llen

Signed-off-by: Benjamin Kramer <benny.kra@googlemail.com>
---
 builtin-diff-tree.c    |    1 -
 builtin-for-each-ref.c |    1 -
 builtin-mailinfo.c     |    1 -
 builtin-shortlog.c     |    1 -
 connect.c              |    2 +-
 imap-send.c            |    2 +-
 pretty.c               |    1 -
 remote.c               |    2 +-
 8 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/builtin-diff-tree.c b/builtin-diff-tree.c
index 8ecefd4..79cedb7 100644
--- a/builtin-diff-tree.c
+++ b/builtin-diff-tree.c
@@ -102,7 +102,6 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 
 	init_revisions(opt, prefix);
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
-	nr_sha1 = 0;
 	opt->abbrev = 0;
 	opt->diff = 1;
 	argc = setup_revisions(argc, argv, opt, NULL);
diff --git a/builtin-for-each-ref.c b/builtin-for-each-ref.c
index e46b7ad..5cbb4b0 100644
--- a/builtin-for-each-ref.c
+++ b/builtin-for-each-ref.c
@@ -943,7 +943,6 @@ static int opt_parse_sort(const struct option *opt, const char *arg, int unset)
 		return -1;
 
 	*sort_tail = s = xcalloc(1, sizeof(*s));
-	sort_tail = &s->next;
 
 	if (*arg == '-') {
 		s->reverse = 1;
diff --git a/builtin-mailinfo.c b/builtin-mailinfo.c
index 2789ccd..1eeeb4d 100644
--- a/builtin-mailinfo.c
+++ b/builtin-mailinfo.c
@@ -537,7 +537,6 @@ static int decode_header_bq(struct strbuf *it)
 				 */
 				strbuf_add(&outbuf, in, ep - in);
 			}
-			in = ep;
 		}
 		/* E.g.
 		 * ep : "=?iso-2022-jp?B?GyR...?= foo"
diff --git a/builtin-shortlog.c b/builtin-shortlog.c
index badd912..b28091b 100644
--- a/builtin-shortlog.c
+++ b/builtin-shortlog.c
@@ -101,7 +101,6 @@ static void insert_one_record(struct shortlog *log,
 	}
 	while (*oneline && isspace(*oneline) && *oneline != '\n')
 		oneline++;
-	len = eol - oneline;
 	format_subject(&subject, oneline, " ");
 	buffer = strbuf_detach(&subject, NULL);
 
diff --git a/connect.c b/connect.c
index 0a35cc1..7636bf9 100644
--- a/connect.c
+++ b/connect.c
@@ -504,7 +504,7 @@ struct child_process *git_connect(int fd[2], const char *url_orig,
 				  const char *prog, int flags)
 {
 	char *url = xstrdup(url_orig);
-	char *host, *path = url;
+	char *host, *path;
 	char *end;
 	int c;
 	struct child_process *conn;
diff --git a/imap-send.c b/imap-send.c
index cb518eb..8154cb2 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -579,7 +579,7 @@ static struct imap_cmd *v_issue_imap_cmd(struct imap_store *ctx,
 			n = socket_write(&imap->buf.sock, cmd->cb.data, cmd->cb.dlen);
 			free(cmd->cb.data);
 			if (n != cmd->cb.dlen ||
-			    (n = socket_write(&imap->buf.sock, "\r\n", 2)) != 2) {
+			    socket_write(&imap->buf.sock, "\r\n", 2) != 2) {
 				free(cmd->cmd);
 				free(cmd);
 				return NULL;
diff --git a/pretty.c b/pretty.c
index c018408..3a24cd5 100644
--- a/pretty.c
+++ b/pretty.c
@@ -154,7 +154,6 @@ void pp_user_info(const char *what, enum cmit_fmt fmt, struct strbuf *sb,
 		while (line < name_tail && isspace(name_tail[-1]))
 			name_tail--;
 		display_name_length = name_tail - line;
-		filler = "";
 		strbuf_addstr(sb, "From: ");
 		add_rfc2047(sb, line, display_name_length, encoding);
 		strbuf_add(sb, name_tail, namelen - display_name_length);
diff --git a/remote.c b/remote.c
index d7079c6..7efaa02 100644
--- a/remote.c
+++ b/remote.c
@@ -495,7 +495,7 @@ static struct refspec *parse_refspec_internal(int nr_refspec, const char **refsp
 		int is_glob;
 		const char *lhs, *rhs;
 
-		llen = is_glob = 0;
+		is_glob = 0;
 
 		lhs = refspec[i];
 		if (*lhs == '+') {
-- 
1.6.2.169.g92418

Re: [PATCH] Remove unused assignments

[Junio C Hamano]

Benjamin Kramer <benny.kra@googlemail.com> writes:

> These variables were always overwritten or the assigned
> value was unused:
>
> builtin-diff-tree.c::cmd_diff_tree(): nr_sha1
> builtin-for-each-ref.c::opt_parse_sort(): sort_tail
> builtin-mailinfo.c::decode_header_bq(): in
> builtin-shortlog.c::insert_one_record(): len
> connect.c::git_connect(): path
> imap-send.c::v_issue_imap_cmd(): n
> pretty.c::pp_user_info(): filler
> remote::parse_refspec_internal(): llen
>
> Signed-off-by: Benjamin Kramer <benny.kra@googlemail.com>

Thanks.  I eyeballed all of them and they look safe, but this patch made
me wonder...

Did you use some dataflow analysis tool to spot these?

It will never scale if a human has to sanity check output from a
mechanical process like this patch, especially when the human is already a
chokepoint of the whole process (i.e. the maintainer).

We'd need some process improvements in the longer term to handle patches
like this, but I do not think of a good one offhand.

I do not think we want to trust tool output blindly; it will not solve the
issue to give me the recipe for the mechanical process you used, to have
me run it and to make me trust the result without checking.  We would want
to keep some human whose judgement we can trust in the loop to always
check the changes mechanical analysis tools may produce.

I think the only viable long term solution would be to keep doing the
manual verification I did like this round until somebody like you
accumulate enough "trust points" in the community for consistently sending
good patches like this one to allow me to apply patches from these people
blindly, trusting the sender's judgement.

But please disregard all of the above if you spotted these by manual
inspection.

I think the patch to pp_user_info() can go one step further.  The filler
is used at only one place after this patch, as a strong given to one of
the placeholders in strbuf_addf().  We can simply feed a constant to the
function instead, like this:

diff --git a/pretty.c b/pretty.c
index 3a24cd5..efa7024 100644
--- a/pretty.c
+++ b/pretty.c
@@ -135,7 +135,6 @@ void pp_user_info(const char *what, enum cmit_fmt fmt, struct strbuf *sb,
 	int namelen;
 	unsigned long time;
 	int tz;
-	const char *filler = "    ";
 
 	if (fmt == CMIT_FMT_ONELINE)
 		return;
@@ -161,7 +160,7 @@ void pp_user_info(const char *what, enum cmit_fmt fmt, struct strbuf *sb,
 	} else {
 		strbuf_addf(sb, "%s: %.*s%.*s\n", what,
 			      (fmt == CMIT_FMT_FULLER) ? 4 : 0,
-			      filler, namelen, line);
+			      "    ", namelen, line);
 	}
 	switch (fmt) {
 	case CMIT_FMT_MEDIUM:

Re: [PATCH] Remove unused assignments

[Benjamin Kramer]

Junio C Hamano wrote:
> 
> Thanks.  I eyeballed all of them and they look safe, but this patch made
> me wonder...
> 
> Did you use some dataflow analysis tool to spot these?
> 
> It will never scale if a human has to sanity check output from a
> mechanical process like this patch, especially when the human is already a
> chokepoint of the whole process (i.e. the maintainer).

Yep, they were found with a little help of the clang static analyzer

http://clang.llvm.org/StaticAnalysis.html

It is in early stages of development so it may report false positives and
it chokes on some files. Here is the latest output I have, with my patch
applied:

http://doktorz.mooltied.de/stuff/scan-build-2009-03-13-2/

I've looked briefly at the "Logic Errors" and they all seem to be false
positives. I did not have enough time to look into all the remaining "Dead
Stores" though.

-- Benjamin