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From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: Johannes Sixt <j.sixt@viscovery.net>, git@vger.kernel.org
Subject: Re: [PATCH 8/4] match-trees: drop "x = x" initializations
Date: Fri, 22 Mar 2013 14:33:16 -0700	[thread overview]
Message-ID: <7vtxo35dcz.fsf@alter.siamese.dyndns.org> (raw)
In-Reply-To: <7v1ub76s8c.fsf@alter.siamese.dyndns.org> (Junio C. Hamano's message of "Fri, 22 Mar 2013 14:26:43 -0700")

Junio C Hamano <gitster@pobox.com> writes:

> These three are all updated by the same tree_entry_extract() call,
> and whenever we use mode[12] we use path[12], so if it decides path1
> is used or assigned, it should be able to tell mode1 is, too.
>
> Unsatisfactory, it surely is...

And immediately after I wrote the above, I am greeted by this:

    gcc (Debian 4.4.5-8) 4.4.5
    match-trees.c:75: error: 'elem1' may be used uninitialized in this function
    match-trees.c:77: error: 'path1' may be used uninitialized in this function

and this crazy one on top squelches it.

If you flip the order of four lines that extracts only when size is
non-zero to extract first from two into elem2, then the warning is
given for elem2/path2 but not for elem1/path1.

I'll initialize all of them to nonsense values for now.

diff --git a/match-trees.c b/match-trees.c
index 4360f10..88981e8 100644
--- a/match-trees.c
+++ b/match-trees.c
@@ -72,9 +72,9 @@ static int score_trees(const unsigned char *hash1, const unsigned char *hash2)
 		die("%s is not a tree", sha1_to_hex(hash2));
 	init_tree_desc(&two, two_buf, size);
 	while (one.size || two.size) {
-		const unsigned char *elem1;
+		const unsigned char *elem1 = NULL;
 		const unsigned char *elem2;
-		const char *path1;
+		const char *path1 = NULL;
 		const char *path2;
 		unsigned mode1 = 0; /* make gcc happy */
 		unsigned mode2 = 0; /* make gcc happy */

  reply	other threads:[~2013-03-22 21:33 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-21 11:03 [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings Jeff King
2013-03-21 11:05 ` [PATCH 1/4] wt-status: fix possible use of uninitialized variable Jeff King
2013-03-21 19:49   ` Jonathan Nieder
2013-03-21 19:55     ` Junio C Hamano
2013-03-21 19:58       ` Jonathan Nieder
2013-03-22 16:15     ` Jeff King
2013-03-21 11:08 ` [PATCH 2/4] fast-import: use pointer-to-pointer to keep list tail Jeff King
2013-03-21 20:43   ` Jonathan Nieder
2013-03-21 11:10 ` [PATCH 3/4] drop some obsolete "x = x" compiler warning hacks Jeff King
2013-03-21 15:16   ` Erik Faye-Lund
2013-03-21 20:47   ` Jonathan Nieder
2013-03-24  7:17     ` Torsten Bögershausen
2013-03-21 11:13 ` [PATCH 4/4] transport: drop "int cmp = cmp" hack Jeff King
2013-03-21 20:59   ` Jonathan Nieder
2013-03-24  4:00   ` Junio C Hamano
2013-03-24  9:32     ` Jeff King
2013-03-24 14:54       ` Torsten Bögershausen
2013-03-25 19:50       ` Junio C Hamano
2013-03-25 21:06         ` Jeff King
2013-03-25 21:55           ` Junio C Hamano
2013-03-21 11:45 ` [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings Johannes Sixt
2013-03-21 11:55   ` Jeff King
2013-03-21 14:58     ` Junio C Hamano
2013-03-21 15:19       ` Junio C Hamano
2013-03-21 15:44         ` Jeff King
2013-03-21 15:44           ` [PATCH 5/4] fast-import: clarify "inline" logic in file_change_m Jeff King
2013-03-21 15:45           ` [PATCH 6/4] run-command: always set failed_errno in start_command Jeff King
2013-03-21 21:02           ` [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings Jonathan Nieder
2013-03-22 16:18           ` Jeff King
2013-03-22 16:19             ` [PATCH 7/4] submodule: clarify logic in show_submodule_summary Jeff King
2013-03-22 21:10               ` Junio C Hamano
2013-03-22 16:21             ` [PATCH 8/4] match-trees: drop "x = x" initializations Jeff King
2013-03-22 21:26               ` Junio C Hamano
2013-03-22 21:33                 ` Junio C Hamano [this message]
2013-03-22 21:36                   ` Jeff King
2013-03-23 18:57               ` René Scharfe
2013-03-24  4:55                 ` Junio C Hamano
2013-03-24 10:01                   ` Jeff King
2013-03-24 22:46                   ` René Scharfe
2013-03-25 16:10                     ` Junio C Hamano
2013-03-21 13:44   ` [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings Joachim Schmitz
2013-03-21 13:56     ` Joachim Schmitz

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