4 files changed, 115 insertions, 60 deletions
diff --git a/contrib/coccinelle/README b/contrib/coccinelle/README
index 9c2f8879c2..f0e80bd7f0 100644
--- a/contrib/coccinelle/README
+++ b/contrib/coccinelle/README
@@ -1,2 +1,43 @@
 This directory provides examples of Coccinelle (http://coccinelle.lip6.fr/)
 semantic patches that might be useful to developers.
+
+There are two types of semantic patches:
+
+ * Using the semantic transformation to check for bad patterns in the code;
+   The target 'make coccicheck' is designed to check for these patterns and
+   it is expected that any resulting patch indicates a regression.
+   The patches resulting from 'make coccicheck' are small and infrequent,
+   so once they are found, they can be sent to the mailing list as per usual.
+
+   Example for introducing new patterns:
+   67947c34ae (convert "hashcmp() != 0" to "!hasheq()", 2018-08-28)
+   b84c783882 (fsck: s/++i > 1/i++/, 2018-10-24)
+
+   Example of fixes using this approach:
+   248f66ed8e (run-command: use strbuf_addstr() for adding a string to
+               a strbuf, 2018-03-25)
+   f919ffebed (Use MOVE_ARRAY, 2018-01-22)
+
+   These types of semantic patches are usually part of testing, c.f.
+   0860a7641b (travis-ci: fail if Coccinelle static analysis found something
+               to transform, 2018-07-23)
+
+ * Using semantic transformations in large scale refactorings throughout
+   the code base.
+
+   When applying the semantic patch into a real patch, sending it to the
+   mailing list in the usual way, such a patch would be expected to have a
+   lot of textual and semantic conflicts as such large scale refactorings
+   change function signatures that are used widely in the code base.
+   A textual conflict would arise if surrounding code near any call of such
+   function changes. A semantic conflict arises when other patch series in
+   flight introduce calls to such functions.
+
+   So to aid these large scale refactorings, semantic patches can be used.
+   However we do not want to store them in the same place as the checks for
+   bad patterns, as then automated builds would fail.
+   That is why semantic patches 'contrib/coccinelle/*.pending.cocci'
+   are ignored for checks, and can be applied using 'make coccicheck-pending'.
+
+   This allows to expose plans of pending large scale refactorings without
+   impacting the bad pattern checks.
diff --git a/contrib/coccinelle/commit.cocci b/contrib/coccinelle/commit.cocci
index a7e9215ffc..c49aa558f0 100644
--- a/contrib/coccinelle/commit.cocci
+++ b/contrib/coccinelle/commit.cocci
@@ -12,13 +12,13 @@ expression c;
 
 // These excluded functions must access c->maybe_tree direcly.
 @@
-identifier f !~ "^(get_commit_tree|get_commit_tree_in_graph|load_tree_for_commit)$";
+identifier f !~ "^(get_commit_tree|get_commit_tree_in_graph_one|load_tree_for_commit)$";
 expression c;
 @@
-  f(...) {...
+  f(...) {<...
 - c->maybe_tree
 + get_commit_tree(c)
-  ...}
+  ...>}
 
 @@
 expression c;
diff --git a/contrib/coccinelle/object_id.cocci b/contrib/coccinelle/object_id.cocci
index 09afdbf994..3e536a9834 100644
--- a/contrib/coccinelle/object_id.cocci
+++ b/contrib/coccinelle/object_id.cocci
@@ -1,110 +1,119 @@
 @@
-expression E1;
+struct object_id OID;
 @@
-- is_null_sha1(E1.hash)
-+ is_null_oid(&E1)
+- is_null_sha1(OID.hash)
++ is_null_oid(&OID)
 
 @@
-expression E1;
+struct object_id *OIDPTR;
 @@
-- is_null_sha1(E1->hash)
-+ is_null_oid(E1)
+- is_null_sha1(OIDPTR->hash)
++ is_null_oid(OIDPTR)
 
 @@
-expression E1;
+struct object_id OID;
 @@
-- sha1_to_hex(E1.hash)
-+ oid_to_hex(&E1)
+- sha1_to_hex(OID.hash)
++ oid_to_hex(&OID)
 
 @@
 identifier f != oid_to_hex;
-expression E1;
+struct object_id *OIDPTR;
 @@
-  f(...) {...
-- sha1_to_hex(E1->hash)
-+ oid_to_hex(E1)
-  ...}
+  f(...) {<...
+- sha1_to_hex(OIDPTR->hash)
++ oid_to_hex(OIDPTR)
+  ...>}
 
 @@
-expression E1, E2;
+expression E;
+struct object_id OID;
 @@
-- sha1_to_hex_r(E1, E2.hash)
-+ oid_to_hex_r(E1, &E2)
+- sha1_to_hex_r(E, OID.hash)
++ oid_to_hex_r(E, &OID)
 
 @@
 identifier f != oid_to_hex_r;
-expression E1, E2;
+expression E;
+struct object_id *OIDPTR;
 @@
-   f(...) {...
-- sha1_to_hex_r(E1, E2->hash)
-+ oid_to_hex_r(E1, E2)
-  ...}
+   f(...) {<...
+- sha1_to_hex_r(E, OIDPTR->hash)
++ oid_to_hex_r(E, OIDPTR)
+  ...>}
 
 @@
-expression E1;
+struct object_id OID;
 @@
-- hashclr(E1.hash)
-+ oidclr(&E1)
+- hashclr(OID.hash)
++ oidclr(&OID)
 
 @@
 identifier f != oidclr;
-expression E1;
+struct object_id *OIDPTR;
 @@
-  f(...) {...
-- hashclr(E1->hash)
-+ oidclr(E1)
-  ...}
+  f(...) {<...
+- hashclr(OIDPTR->hash)
++ oidclr(OIDPTR)
+  ...>}
 
 @@
-expression E1, E2;
+struct object_id OID1, OID2;
 @@
-- hashcmp(E1.hash, E2.hash)
-+ oidcmp(&E1, &E2)
+- hashcmp(OID1.hash, OID2.hash)
++ oidcmp(&OID1, &OID2)
 
 @@
 identifier f != oidcmp;
-expression E1, E2;
+struct object_id *OIDPTR1, OIDPTR2;
 @@
-  f(...) {...
-- hashcmp(E1->hash, E2->hash)
-+ oidcmp(E1, E2)
-  ...}
+  f(...) {<...
+- hashcmp(OIDPTR1->hash, OIDPTR2->hash)
++ oidcmp(OIDPTR1, OIDPTR2)
+  ...>}
 
 @@
-expression E1, E2;
+struct object_id *OIDPTR;
+struct object_id OID;
 @@
-- hashcmp(E1->hash, E2.hash)
-+ oidcmp(E1, &E2)
+- hashcmp(OIDPTR->hash, OID.hash)
++ oidcmp(OIDPTR, &OID)
 
 @@
-expression E1, E2;
+struct object_id *OIDPTR;
+struct object_id OID;
 @@
-- hashcmp(E1.hash, E2->hash)
-+ oidcmp(&E1, E2)
+- hashcmp(OID.hash, OIDPTR->hash)
++ oidcmp(&OID, OIDPTR)
 
 @@
-expression E1, E2;
+struct object_id *OIDPTR1;
+struct object_id *OIDPTR2;
 @@
-- hashcpy(E1.hash, E2.hash)
-+ oidcpy(&E1, &E2)
+- oidcmp(OIDPTR1, OIDPTR2) == 0
++ oideq(OIDPTR1, OIDPTR2)
 
 @@
-identifier f != oidcpy;
+identifier f != hasheq;
 expression E1, E2;
 @@
-  f(...) {...
-- hashcpy(E1->hash, E2->hash)
-+ oidcpy(E1, E2)
-  ...}
+  f(...) {<...
+- hashcmp(E1, E2) == 0
++ hasheq(E1, E2)
+  ...>}
 
 @@
-expression E1, E2;
+struct object_id *OIDPTR1;
+struct object_id *OIDPTR2;
 @@
-- hashcpy(E1->hash, E2.hash)
-+ oidcpy(E1, &E2)
+- oidcmp(OIDPTR1, OIDPTR2) != 0
++ !oideq(OIDPTR1, OIDPTR2)
 
 @@
+identifier f != hasheq;
 expression E1, E2;
 @@
-- hashcpy(E1.hash, E2->hash)
-+ oidcpy(&E1, E2)
+  f(...) {<...
+- hashcmp(E1, E2) != 0
++ !hasheq(E1, E2)
+  ...>}
diff --git a/contrib/coccinelle/preincr.cocci b/contrib/coccinelle/preincr.cocci
new file mode 100644
index 0000000000..7fe1e8d2d9
--- /dev/null
+++ b/contrib/coccinelle/preincr.cocci
@@ -0,0 +1,5 @@
+@ preincrement @
+identifier i;
+@@
+- ++i > 1
++ i++