Re: Coccinelle for PostgreSQL development [1/N]: coccicheck.py

On 2025-01-07 Tu 2:44 PM, Mats Kindahl wrote:
> I got some time over during the holidays, so I spent some of it
> doing something I've been thinking about for a while.
>
> For those of you that are not aware of it: Coccinelle is a tool for
> pattern matching and text transformation for C code and can be used
> for detection of problematic programming patterns and to make complex,
> tree-wide patches easy. It is aware of the structure of C code and is
> better suited to make complicated changes than what is possible using
> normal text substitution tools like Sed and Perl.
>
> Coccinelle have been successfully been used in the Linux project since
> 2008 and is now an established tool for Linux development and a large
> number of semantic patches have been added to the source tree to
> capture everything from generic issues (like eliminating the redundant
> A in expressions like "!A || (A && B)") to more Linux-specific
> problems like adding a missing call to kfree().
>
> Although PostgreSQL is nowhere the size of the Linux kernel, it is
> nevertheless of a significant size and would benefit from
> incorporating Coccinelle into the development. I noticed it's been
> used in a few cases way back (like 10 years back) to fix issues in the
> PostgreSQL code, but I thought it might be useful to make it part of
> normal development practice to, among other things:
>
> - Identify and correct bugs in the source code both during development
> and review.
> - Make large-scale changes to the source tree to improve the code
> based on new insights.
> - Encode and enforce APIs by ensuring that function calls are used
> correctly.
> - Use improved coding patterns for more efficient code.
> - Allow extensions to automatically update code for later PostgreSQL
> versions.
>
> To that end, I created a series of patches to show how it could be
> used in the PostgreSQL tree. It is a lot easier to discuss concrete
> code and I split it up into separate messages since that makes it
> easier to discuss each individual patch. The series contains code to
> make it easy to work with Coccinelle during development and reviews,
> as well as examples of semantic patches that capture problems,
> demonstrate how to make large-scale changes, how to enforce APIs, and
> also improve some coding patterns.
>
> This first patch contains the coccicheck.py script, which is a
> re-implementation of the coccicheck script that the Linux kernel uses.
> We cannot immediately use the coccicheck script since it is quite
> closely tied to the Linux source code tree and we need to have
> something that both supports autoconf and Meson. Since Python seems to
> be used more and more in the tree, it seems to be the most natural
> choice. (I have no strong opinion on what language to use, but think
> it would be good to have something that is as platform-independent as
> possible.)
>
> The intention is that we should be able to use the Linux semantic
> patches directly, so it supports the "Requires" and "Options"
> keywords, which can be used to require a specific version of spatch(1)
> and add options to the execution of that semantic patch, respectively.
>

Please don't start multiple threads like this. If you want to submit a
set of patches for a single feature, send them all as attachments in a
single email. Otherwise this just makes life hard for threading email
readers.

cheers

andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com