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[PATCH] coccicheck: introduce 'pending' semantic patches

From
Stefan Beller <sbeller@google.com>
Date
Nov 10, 2018, 00:10 UTC
Message-ID
<20181110001052.101290-1-sbeller@google.com>
In-Reply-To
<20181108205255.193402-1-sbeller@google.com>
From: SZEDER Gábor <szeder.dev@gmail.com>

Teach `make coccicheck` to avoid patches named "*.pending.cocci" and handle them separately in a new `make coccicheck-pending` instead. This means that we can separate "critical" patches from "FYI" patches. The former target can continue causing Travis to fail its static analysis job, while the latter can let us keep an eye on ongoing (pending) transitions without them causing too much fallout.

Document the intended use-cases around these two targets. As the process around the pending patches is not yet fully explored, leave that out.

Based-on-work-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

I dialed back on the workflow, as we may want to explore it first before writing it down.

Stefan
 Makefile                  |  7 +++++--
 contrib/coccinelle/README | 41 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 2 deletions(-)
diff --git a/Makefile b/Makefile
index bbfbb4292d..6bc4654828 100644
--- a/Makefile
+++ b/Makefile
@@ -2740,9 +2740,12 @@ endif
 	then \
 		echo '    ' SPATCH result: $@; \
 	fi
-coccicheck: $(addsuffix .patch,$(wildcard contrib/coccinelle/*.cocci))
+coccicheck: $(addsuffix .patch,$(filter-out %.pending.cocci,$(wildcard contrib/coccinelle/*.cocci)))
 
-.PHONY: coccicheck
+# See contrib/coccinelle/README
+coccicheck-pending: $(addsuffix .patch,$(wildcard contrib/coccinelle/*.pending.cocci))
+
+.PHONY: coccicheck coccicheck-pending
 
 ### Installation rules
 
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.

-- 
2.19.1.930.g4563a0d9d0-goog
Previous: Junio C HamanoNext: Martin Ågren
Message 11 of 43 in “[PATCHv2 00/24] Bring more repository handles into our code base]”
  1. Stefan BellerOct 30, 2018
  2. 01/24 Makefile: add pending semantic patchesStefan Beller, Oct 30, 2018
  3. Junio C HamanoOct 31, 2018
  4. Makefile: add pending semantic patchesStefan Beller, Nov 8, 2018
  5. Martin ÅgrenNov 9, 2018
  6. Stefan BellerNov 9, 2018
  7. Junio C HamanoNov 9, 2018
  8. Stefan BellerNov 9, 2018
  9. SZEDER GáborNov 13, 2018
  10. Junio C HamanoNov 14, 2018
  11. coccicheck: introduce 'pending' semantic patchesStefan Beller, Nov 10, 2018
  12. Martin ÅgrenNov 10, 2018
  13. Josh SteadmonNov 12, 2018
  14. SZEDER GáborNov 13, 2018
  15. 02/24 sha1_file: allow read_object to read objects in arbitrary repositoriesStefan Beller, Oct 30, 2018
  16. 03/24 packfile: allow has_packed_and_bad to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  17. 04/24 object-store: allow read_object_file_extended to read from arbitrary repositoriesStefan Beller, Oct 30, 2018
  18. 05/24 object-store: prepare read_object_file to deal with arbitrary repositoriesStefan Beller, Oct 30, 2018
  19. 06/24 object-store: prepare has_{sha1, object}_file[_with_flags] to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  20. 07/24 object: parse_object to honor its repository argumentStefan Beller, Oct 30, 2018
  21. 08/24 commit: allow parse_commit* to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  22. 09/24 commit-reach.c: allow paint_down_to_common to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  23. 10/24 commit-reach.c: allow merge_bases_many to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  24. 11/24 commit-reach.c: allow remove_redundant to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  25. 13/24 commit-reach: prepare get_merge_bases to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  26. 14/24 commit-reach: prepare in_merge_bases[_many] to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  27. 15/24 commit: prepare get_commit_buffer to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  28. 12/24 commit-reach.c: allow get_merge_bases_many_0 to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  29. 16/24 commit: prepare repo_unuse_commit_buffer to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  30. 17/24 commit: prepare logmsg_reencode to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  31. 18/24 pretty: prepare format_commit_message to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  32. 19/24 submodule: use submodule repos for object lookupStefan Beller, Oct 30, 2018
  33. Derrick StoleeNov 2, 2018
  34. Stefan BellerNov 2, 2018
  35. Derrick StoleeNov 2, 2018
  36. 20/24 submodule: don't add submodule as odb for pushStefan Beller, Oct 30, 2018
  37. 21/24 commit-graph: convert remaining function to handle arbitrary repositoriesStefan Beller, Oct 30, 2018
  38. 22/24 commit: make free_commit_buffer and release_commit_memory repository agnosticStefan Beller, Oct 30, 2018
  39. 23/24 path.h: make REPO_GIT_PATH_FUNC repository agnosticStefan Beller, Oct 30, 2018
  40. 24/24 t/helper/test-repository: celebrate independence from the_repositoryStefan Beller, Oct 30, 2018
  41. Junio C HamanoOct 31, 2018
  42. Stefan BellerNov 1, 2018
  43. Junio C HamanoNov 2, 2018

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