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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: git@vger.kernel.org
Cc: "Junio C Hamano" <gitster@pobox.com>,
	"Derrick Stolee" <derrickstolee@github.com>,
	"Jeff King" <peff@peff.net>, "Elijah Newren" <newren@gmail.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: [PATCH v3 2/4] cocci: catch unused "strbuf" using an xmalloc() pattern
Date: Fri,  1 Jul 2022 12:30:57 +0200	[thread overview]
Message-ID: <patch-v3-2.4-6324d3956ed-20220701T102506Z-avarab@gmail.com> (raw)
In-Reply-To: <cover-v3-0.4-00000000000-20220701T102506Z-avarab@gmail.com>

There's no current matches for this rule, but it will match both:

	struct strbuf *buf = xmalloc(sizeof(struct strbuf));
	strbuf_init(buf, 0);
	strbuf_release(buf);

And:

	struct strbuf *buf;

	buf = xmalloc(sizeof(struct strbuf));
	strbuf_init(buf, 0);
	strbuf_release(buf);

Note that we'd also match a strbuf_init() before the xmalloc(), but
we're not seeking to be so strict as to make checks that the compiler
will catch for us redundant, and saying we'll match either "init" or
"xmalloc" lines makes the rule simpler.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 contrib/coccinelle/unused.cocci | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/contrib/coccinelle/unused.cocci b/contrib/coccinelle/unused.cocci
index bc26d39b313..43942f3cd4f 100644
--- a/contrib/coccinelle/unused.cocci
+++ b/contrib/coccinelle/unused.cocci
@@ -22,6 +22,8 @@ type T;
 identifier I;
 // STRBUF_INIT
 constant INIT_MACRO =~ "^STRBUF_INIT$";
+// x[mc]alloc() etc.
+identifier MALLOC1 =~ "^x?[mc]alloc$";
 // strbuf_init(&I, ...) etc.
 identifier INIT_CALL1 =~ "^strbuf_init$";
 // strbuf_release()
@@ -37,15 +39,25 @@ identifier REL1 =~ "^strbuf_release$";
 // ... or "struct STRBUF buf = STRBUF_INIT;" ...
 |
 - T I = INIT_MACRO;
+|
+// ... or "struct strbuf *buf = xmalloc(...)" etc. ...
+- T I = MALLOC1(...);
 )
 
 // ... Optionally followed by lines that make no use of "buf", "&buf"
 // etc., but which ...
 <... when != \( I \| &I \)
      when strict
+(
 // .. (only) make use of "buf" or "&buf" to call something like
 // "strbuf_init(&buf, ...)" ...
 - \( INIT_CALL1 \)( \( I \| &I \), ...);
+|
+// .. or to follow-up a "struct strbuf *buf" with e.g. "buf =
+// xmalloc(...)" (which may in turn be followed-up by a
+// "strbuf_init()", which we'll match with INIT_CALL1) ...
+- I = MALLOC1(...);
+)
 ...>
 
 // ... and then no mention of "buf" or "&buf" until we get to a
-- 
2.37.0.900.g4d0de1cceb2


  parent reply	other threads:[~2022-07-01 10:36 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-20 11:57 [PATCH] cocci: add and apply a rule to find "unused" variables Ævar Arnfjörð Bjarmason
2022-06-21 22:44 ` [PATCH v2 0/2] add and apply a rule to find "unused" init+free Ævar Arnfjörð Bjarmason
2022-06-21 22:44   ` [PATCH v2 1/2] cocci: add and apply a rule to find "unused" variables Ævar Arnfjörð Bjarmason
2022-06-22 16:02     ` Junio C Hamano
2022-06-21 22:44   ` [PATCH v2 2/2] cocci: remove "when strict" from unused.cocci Ævar Arnfjörð Bjarmason
2022-07-01 10:30   ` [PATCH v3 0/4] add and apply a rule to find "unused" init+free Ævar Arnfjörð Bjarmason
2022-07-01 10:30     ` [PATCH v3 1/4] cocci: add and apply a rule to find "unused" strbufs Ævar Arnfjörð Bjarmason
2022-07-01 18:04       ` Jeff King
2022-07-01 19:55       ` Eric Sunshine
2022-07-01 10:30     ` Ævar Arnfjörð Bjarmason [this message]
2022-07-01 10:30     ` [PATCH v3 3/4] cocci: remove "when strict" from unused.cocci Ævar Arnfjörð Bjarmason
2022-07-01 21:33       ` Eric Sunshine
2022-07-01 10:30     ` [PATCH v3 4/4] cocci: generalize "unused" rule to cover more than "strbuf" Ævar Arnfjörð Bjarmason
2022-07-01 18:09     ` [PATCH v3 0/4] add and apply a rule to find "unused" init+free Jeff King
2022-07-05 13:46     ` [PATCH v4 0/6] " Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 1/6] Makefile: remove mandatory "spatch" arguments from SPATCH_FLAGS Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 2/6] Makefile & .gitignore: ignore & clean "git.res", not "*.res" Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 3/6] cocci: add a "coccicheck-test" target and test *.cocci rules Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 4/6] cocci: have "coccicheck{,-pending}" depend on "coccicheck-test" Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 5/6] cocci: add and apply a rule to find "unused" strbufs Ævar Arnfjörð Bjarmason
2022-07-05 13:47       ` [PATCH v4 6/6] cocci: generalize "unused" rule to cover more than "strbuf" Ævar Arnfjörð Bjarmason
2022-07-06 19:30       ` [PATCH v4 0/6] add and apply a rule to find "unused" init+free Junio C Hamano
2022-07-11  9:41       ` Jeff King
2022-07-11 10:54         ` Ævar Arnfjörð Bjarmason

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