Re: Coccinelle for automated refactors

"brian m. carlson" [off-list ref] writes:

An example semantic patch looks like this:

@@
expression E1;
@@
- is_null_sha1(E1.hash)
+ is_null_oid(&E1)

@@
expression E1;
@@
- is_null_sha1(E1->hash)
+ is_null_oid(E1)

This does what you think it does: transforms calls to is_null_sha1 that
use the struct object_id hash member into calls to is_null_oid.

I'd like to use this for some of the struct object_id work if others
think this is a good idea.  I feel it's likely to reduce the reviewing
overhead and allow people to better reason about the quality and
behavior of the sent patches.  Of course, I would still review the
patches manually for errors and improvements, and would still accept
responsibility for the content of the patches.

Is the plan for such a "refactor" patch to compose such a series as
two patch series:

 [1/2] automatic refactor

which gives the "semantic patch" in the proposed log message as part
of its description, and the automated result (with possible
misconversions that may have come from bugs in the automated tools),
with a separate

 [2/2] manual fixups

that corrects what was misconverted and what was missed?

As long as [2/2] can be kept to the minimum (and an automated tool
that is worth using should make it so), I think that is a good way
forward.  Another possibility would be to send the end-result as a
single patch, with description on the manual fixups in the proposed
log message, but it would be a lot more work to generate and review
such a patch, I would think.

If there's interest, I can send a patch with a set of basic object_id
transforms to make it easier for others to make those changes when
they're doing work elsewhere in the codebase.

[0] http://coccinelle.lip6.fr/