[PATCH v3 2/4] cocci: catch unused "strbuf" using an xmalloc() pattern

From

Ævar Arnfjörð Bjarmason <avarab@gmail.com>

Date

Jul 1, 2022, 10:30 UTC

Message-ID

<patch-v3-2.4-6324d3956ed-20220701T102506Z-avarab@gmail.com>

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);

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