Flit removes VCS check for ignored files when `--format wheel` is used

[potiuk]

When you build your package with flit (latest version 3.12.0) the fact whether .gitignored files are ignored or not depends on the presence of --format flag. It looks like the .gitignored files are excluded only when --format sdist is used or when "default" settings are used (no --format specifided). But this filtering is not applied when you only build wheel files.

You can check it by checking out airflow repo and following the steps:

git clone git@github.com:apache/airflow.git

# generate UI files
cd airflow
pre-commit run compile-fab-assets --all-files 

# at this moment  providers/fab/src/airflow/providers/fab/www/node_modules should be created
# the file is .gitignored at top level folder
cd  providers/fab

# cleanup dist
jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider ± rm -rf dist/*
zsh: sure you want to delete all the files in /home/jarek/code/airflow/providers/fab/dist [yn]? y
zsh: no matches found: dist/*
                                                                                                                                                                                                                                             [jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider 1 ± 


# build both sdist and wheel packages - make sure VCS files are ignored
[jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider ± flit build --use-vcs
Found 207 files tracked in git                                                                                                                                                                                                   I-flit.sdist
Built sdist: dist/apache_airflow_providers_fab-2.0.0.tar.gz                                                                                                                                                                 I-flit_core.sdist
Copying package file(s) from /tmp/tmpkikll3wf/apache_airflow_providers_fab-2.0.0/src/airflow/providers/fab                                                                                                                  I-flit_core.wheel
Writing metadata files                                                                                                                                                                                                      I-flit_core.wheel
Writing the record of files                                                                                                                                                                                                 I-flit_core.wheel
Built wheel: dist/apache_airflow_providers_fab-2.0.0-py3-none-any.whl                                                                                                                                                       I-flit_core.wheel
[jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider ± ls -la dist
total 1308
drwxr-xr-x 1 jarek jarek    184 Apr  7 14:37 .
drwxr-xr-x 1 jarek jarek    142 Apr  7 14:37 ..
-rw------- 1 jarek jarek 603350 Apr  7 14:37 apache_airflow_providers_fab-2.0.0-py3-none-any.whl
-rw-r--r-- 1 jarek jarek 729661 Apr  7 14:37 apache_airflow_providers_fab-2.0.0.tar.gz

# you see that the .whl file ~600 KB

# Do it again but only for wheel
[jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider ± rm -rf dist/*       
zsh: sure you want to delete all 2 files in /home/jarek/code/airflow/providers/fab/dist [yn]? y
                                                                                                                                                                                                                                             
[jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider ± 
[jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider ± flit build --use-vcs --format wheel
Copying package file(s) from src/airflow/providers/fab                                                                                                                                                                      I-flit_core.wheel
Writing metadata files                                                                                                                                                                                                      I-flit_core.wheel
Writing the record of files                                                                                                                                                                                                 I-flit_core.wheel
Built wheel: dist/apache_airflow_providers_fab-2.0.0-py3-none-any.whl                                                                                                                                                       I-flit_core.wheel

# You can see that built packagr is ~30M and there is no message about ignoring files in flit output

[jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider ± ls -la dist 
total 29824
drwxr-xr-x 1 jarek jarek      102 Apr  7 14:37 .
drwxr-xr-x 1 jarek jarek      142 Apr  7 14:37 ..
-rw------- 1 jarek jarek 30539333 Apr  7 14:37 apache_airflow_providers_fab-2.0.0-py3-none-any.whl
[jarek:~/code/airflow/providers/fab] fix-too-big-size-of-fab-provider ± 

It's quite unexpected to have VCS exclusion only applied when sdist is build - especially that it is applied when the wheel package is build together with sdist

I'd expect the VCS exclusion to be applied also when .whl file is build alone

[takluyver]

Using information from git is likely to go away in a future version in any case (see #522, #625), because of oddities like this and discrepancies between calling the flit command and using Flit as a build backend behind other tools.

[potiuk]

That's fine, as long as there is other mechanism for exclusion.