coccicheck: detect hashmap_entry.hash assignment

Eric Wong · gitster · commit 12878c83516e · 2019-10-07T10:20:09.000+09:00
Assigning hashmap_entry.hash manually leaves hashmap_entry.next
uninitialized, which can be dangerous once the hashmap_entry is
inserted into a hashmap.   Detect those assignments and use
hashmap_entry_init, instead.

Signed-off-by: Eric Wong &lt;e@80x24.org&gt;
Reviewed-by: Derrick Stolee &lt;stolee@gmail.com&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/contrib/coccinelle/hashmap.cocci b/contrib/coccinelle/hashmap.cocci
@@ -0,0 +1,16 @@
+@ hashmap_entry_init_usage @
+expression E;
+struct hashmap_entry HME;
+@@
+- HME.hash = E;
++ hashmap_entry_init(&HME, E);
+
+@@
+identifier f !~ "^hashmap_entry_init$";
+expression E;
+struct hashmap_entry *HMEP;
+@@
+  f(...) {<...
+- HMEP->hash = E;
++ hashmap_entry_init(HMEP, E);
+  ...>}
