Re: [PATCH] Add flake8 and isort to .pre-commit-config.yaml

[Simon Marchi <simark@simark.ca>]

On 2024-04-02 14:11, Tom Tromey wrote:
> This adds flake8 and isort to .pre-commit-config.yaml.  This way, they
> will automatically be run on commit.
> 
> I chose the most recent available versions after verifying that they
> don't cause any reports or changes in the current tree.
> 
> Internally at AdaCore, we also use a few flake8 plugins as well, so
> perhaps that's another avenue for investigation.
> ---
>  .pre-commit-config.yaml | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
> index 7afe60c20be..bca8acc5d02 100644
> --- a/.pre-commit-config.yaml
> +++ b/.pre-commit-config.yaml
> @@ -6,3 +6,14 @@ repos:
>      hooks:
>        - id: black
>          files: 'gdb/.*'
> +  - repo:  https://github.com/pycqa/flake8
> +    rev: 7.0.0
> +    hooks:
> +    - id: flake8
> +      files: gdb/python/.*\.py$
> +      args: [--config, gdb/setup.cfg]
> +  - repo: https://github.com/pycqa/isort
> +    rev: 5.13.2
> +    hooks:
> +    - id: isort
> +      files: gdb/.*\.py$

I only used `gdb/.*.py` for the black hook, because pre-commit does its
own filtering already.  The hooks specify the `python` type, so
pre-commit only runs the hook on what it believes is a Python file.  The
only purpose of the regex was to limit the hooks to the gdb
sub-directory.

However, I realized we have at least one file that is python but isn't
named *.py, gdb-gdb.py.in.  I just tried, and the black hook doesn't run
on gdb-gdb.py-in.  If you run black manually, it considers gdb-gdb.py.in
as a Python file (I don't know by which magic) and re-formats it:

    $ pwd
    /home/simark/src/binutils-gdb
    $ black gdb
    reformatted /home/simark/src/binutils-gdb/gdb/gdb-gdb.py.in

But the filtering done by pre-commit doesn't consider gdb-gdb.py.in a
Python file.  The hooks specify `types: 'python'`, which doesn't match
'*.py.in'.  The doc for `types` is here:

    https://pre-commit.com/#filtering-files-with-types

The mapping between extensions and types is here:

    https://github.com/pre-commit/identify/blob/main/identify/extensions.py

If we want to make pre-commit consider that file for our Python hooks,
the only solution I see currently would be to use something like this,
as described in the doc above:

    hooks:
      - id: black
        types_or: [file]
        files: '^gdb/.*\.(py|py.in)$'

It didn't seem to work for me using `types` (an error in gdb-gdb.py.in
wouldn't be caught), but it works using `types_or`.  So, I would
consider something similar for other hooks as well.

Simon