[PATCH] cocci: strbuf.buf is never NULL

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 19, 2026, 22:39 UTC
Message-ID: <xmqq4imbigvt.fsf@gitster.g>

We recently noticed one old code from 19 years ago protecting against an ancient strbuf convention that the .buf member can be NULL for an empty strbuf. As that is no longer the case in the modern codebase, let's catch such a construct.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 * Comes directly on top of my recent rerere.c clean-up patch.

 contrib/coccinelle/strbuf.cocci | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/contrib/coccinelle/strbuf.cocci b/contrib/coccinelle/strbuf.cocci
index 5f06105df6..13f0ad2679 100644
--- a/contrib/coccinelle/strbuf.cocci
+++ b/contrib/coccinelle/strbuf.cocci
@@ -60,3 +60,10 @@ expression E1, E2;
 @@
 - strbuf_addstr(E1, real_path(E2));
 + strbuf_add_real_path(E1, E2);
+
+// In modern codebase, .buf member of an empty strbuf is not NULL.
+@@
+struct strbuf SB;
+@@
+- SB.buf ? SB.buf : ""
++ SB.buf

-- 
2.53.0-816-g44373249a2