2016-06-25 01:09:20 +02:00
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This directory provides examples of Coccinelle (http://coccinelle.lip6.fr/)
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semantic patches that might be useful to developers.
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2018-11-10 01:10:52 +01:00
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There are two types of semantic patches:
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* Using the semantic transformation to check for bad patterns in the code;
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The target 'make coccicheck' is designed to check for these patterns and
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it is expected that any resulting patch indicates a regression.
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The patches resulting from 'make coccicheck' are small and infrequent,
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so once they are found, they can be sent to the mailing list as per usual.
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Example for introducing new patterns:
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67947c34ae (convert "hashcmp() != 0" to "!hasheq()", 2018-08-28)
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b84c783882 (fsck: s/++i > 1/i++/, 2018-10-24)
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Example of fixes using this approach:
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248f66ed8e (run-command: use strbuf_addstr() for adding a string to
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a strbuf, 2018-03-25)
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f919ffebed (Use MOVE_ARRAY, 2018-01-22)
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These types of semantic patches are usually part of testing, c.f.
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0860a7641b (travis-ci: fail if Coccinelle static analysis found something
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to transform, 2018-07-23)
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* Using semantic transformations in large scale refactorings throughout
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the code base.
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When applying the semantic patch into a real patch, sending it to the
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mailing list in the usual way, such a patch would be expected to have a
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lot of textual and semantic conflicts as such large scale refactorings
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change function signatures that are used widely in the code base.
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A textual conflict would arise if surrounding code near any call of such
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function changes. A semantic conflict arises when other patch series in
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flight introduce calls to such functions.
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So to aid these large scale refactorings, semantic patches can be used.
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However we do not want to store them in the same place as the checks for
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bad patterns, as then automated builds would fail.
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That is why semantic patches 'contrib/coccinelle/*.pending.cocci'
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are ignored for checks, and can be applied using 'make coccicheck-pending'.
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This allows to expose plans of pending large scale refactorings without
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impacting the bad pattern checks.
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