mesonbuild::wrap::wrap.py::199 -- subproject command fails when using wrap & custom subprojects_dir setting due to hardcoded dir name

[abdallahsoliman]

Describe the bug

When using wrap file for a nested subproject, and a non-default setting for subprojects_dir (subprojects_dir != 'subprojects'), unexpected failure occurs when calling subproject related command (e.g: meson subprojects purge). The error is as follows:

❯ meson subprojects purge --confirm

ERROR: wrap-redirect filename must be in the form foo/subprojects/bar.wrap

This is due to mesonbuild/wrap/wrap.py::199, which contains a hard-coded check for the subproject directory name:

if p != 'subprojects':
    raise WrapException('wrap-redirect filename must be in the form foo/subprojects/bar.wrap')

To Reproduce

The following project structure & content files is sufficient to reproduce the error:
foo.zip

Project Structure:

foo
├── meson.build
└── module
    └── bar
        ├── meson.build
        └── module
            ├── argparse.wrap
            └── packagefiles
                └── argparse
                    └── meson.build

6 directories, 4 files

File Contents:

# ./meson.build
project(
    'foo',
    ['c', 'cpp'],
    subproject_dir: 'module',
    meson_version: '>=1.6'
)

subproject('bar')

# ./module/bar/meson.build
project(
    'bar',
    ['c', 'cpp'],
    subproject_dir: 'module',
    meson_version: '>=1.6'
)

argparse_dep = subproject('argparse')

# ./module/bar/module/packagefiles/argparse/meson.build
project(
    'argparse',
    ['c', 'cpp'],
    subproject_dir: 'module',
    meson_version: '>=1.6'
)

argparse_dep = include_directories('include')

# ./module/bar/module/argparse.wrap
[wrap-git]
url=https://github.com/p-ranav/argparse.git
revision=v3.1
depth=1
patch_directory = argparse

[provide]
dependency_names = argparse

Commands:

meson setup build
meson subprojects purge --confirm

Workaround:

Applying the following patch to mesonbuild/wrap/wrap.py will allow the command to work as expected. However, please keep in mind that thorough testing was not performed to confirm there are no side-effects. This patch was intended to mitigate the immediate issue.

# mesonbuild_wrap.py.patch
199,200c199,201
<                     if p != 'subprojects':
<                         raise WrapException('wrap-redirect filename must be in the form foo/subprojects/bar.wrap')
---
>                     subprojects_dir_name = os.path.basename(subprojects_dir)
>                     if p != subprojects_dir_name:
>                         raise WrapException(f'wrap-redirect filename must be in the form foo/{subprojects_dir_name}/bar.wrap')

patch $(dirname $(python -c "import mesonbuild; print(mesonbuild.__file__)"))/wrap/wrap.py mesonbuild_wrap.py.patch
meson subprojects purge --confirm

After applying the patch, the command works as expected.

Expected behavior

The following error should only occur if the subprojects_dir name does not match what it was configured to. If subprojects_dir is not the default value 'subprojects' it does not seem appropriate to check the subprojects directory name against the default value.

❯ meson subprojects purge --confirm

ERROR: wrap-redirect filename must be in the form foo/subprojects/bar.wrap

system parameters

• Native Build
• Ubuntu 24.04
• Python 3.12 (virtualenv)
• Meson 1.6.1
• Ninja 1.11.1