So when I run this:

$ pants run projects/delta/src/delta/main.py

18:52:50.40 [WARN] The target projects/delta/src/delta/main.py imports `msgspec.json`, but Pants cannot safely infer a dependency because more than one target owns this module, so it is ambiguous which to use: ['projects/delta:poetry#msgspec', 'projects/gamma:poetry#msgspec'].

Please explicitly include the dependency you want in the `dependencies` field of projects/delta/src/delta/main.py, or ignore the ones you do not want by prefixing with `!` or `!!` so that one or no targets are left.

Alternatively, you can remove the ambiguity by deleting/changing some of the targets so that only 1 target owns this module. Refer to <https://www.pantsbuild.org/2.21/docs/using-pants/troubleshooting-common-issues#import-errors-and-missing-dependencies>.
18:52:50.40 [WARN] Pants cannot infer owners for the following imports in the target projects/delta/src/delta/main.py:

  * msgspec.json (line: 3)

If you do not expect an import to be inferrable, add `# pants: no-infer-dep` to the import line. Otherwise, see <https://www.pantsbuild.org/2.21/docs/using-pants/troubleshooting-common-issues#import-errors-and-missing-dependencies> for common problems.
18:52:51.06 [INFO] Completed: Building 1 requirement for delta.pex from the 3rdparty/python/default.lock resolve: click<9.0.0,>=8.1.7
Traceback (most recent call last):
  File "/tmp/pants-sandbox-zRpAVd/./.cache/pex_root/venvs/3a7bcecec44d89cc814291af2f562c1aa5b28506/0de1795ad4486f45ee94cecd983e9905b6b11dc9/pex", line 320, in <module>
    runpy.run_module(module_name, run_name="__main__", alter_sys=True)
  File "<frozen runpy>", line 226, in run_module
  File "<frozen runpy>", line 98, in _run_module_code
  File "<frozen runpy>", line 88, in _run_code
  File "/tmp/pants-sandbox-zRpAVd/projects/delta/src/delta/main.py", line 3, in <module>
    import msgspec.json
ModuleNotFoundError: No module named 'msgspec'

For these roots:

$ pants roots
.
projects/delta/src
projects/gamma/src

I've been struggling with this for a few days now, with first- and third party dependencies. That's technically correct, both

gamma

and

delta

have

msgspec

as a 3rd party dependency. But shouldn't

source_roots

take care of this? They're in differnt roots. So why would

delta

be concerned with reqs in

gamma

. Yes, they share a resolve. And yes, it stops complaining if I split the resolves. But why should that matter? The same problem occurs with 1st party:

19:04:57.23 [WARN] The target projects/delta/src/delta/main.py imports `omega.util.important_function_for_gamma`, but Pants cannot safely infer a dependency because more than one target owns this module, so it is ambiguous which to use: ['projects/delta/src/omega/util.py', 'projects/gamma/src/omega/util.py'].

Please explicitly include the dependency you want in the `dependencies` field of projects/delta/src/delta/main.py, or ignore the ones you do not want by prefixing with `!` or `!!` so that one or no targets are left.

Alternatively, you can remove the ambiguity by deleting/changing some of the targets so that only 1 target owns this module. Refer to <https://www.pantsbuild.org/2.21/docs/using-pants/troubleshooting-common-issues#import-errors-and-missing-dependencies>.
Traceback (most recent call last):
  File "/tmp/pants-sandbox-fNU927/./.cache/pex_root/venvs/3a7bcecec44d89cc814291af2f562c1aa5b28506/0de1795ad4486f45ee94cecd983e9905b6b11dc9/pex", line 320, in <module>
    runpy.run_module(module_name, run_name="__main__", alter_sys=True)
  File "<frozen runpy>", line 226, in run_module
  File "<frozen runpy>", line 98, in _run_module_code
  File "<frozen runpy>", line 88, in _run_code
  File "/tmp/pants-sandbox-fNU927/projects/delta/src/delta/main.py", line 6, in <module>
    from omega.util import important_function_for_gamma
ModuleNotFoundError: No module named 'omega'

Both

delta

and

gamma

have a package called

omega

. Here's the file tree:

.
├── 3rdparty
│   └── python
│       └── default.lock
├── pants.toml
└── projects
    ├── delta
    │   ├── BUILD
    │   ├── poetry.lock
    │   ├── pyproject.toml
    │   ├── src
    │   │   ├── delta
    │   │   │   ├── BUILD
    │   │   │   ├── __init__.py
    │   │   │   └── main.py
    │   │   └── omega
    │   │       ├── BUILD
    │   │       ├── __init__.py
    │   │       └── util.py
    │   └── tests
    │       ├── BUILD
    │       ├── __init__.py
    │       └── test_first.py
    └── gamma
        ├── BUILD
        ├── poetry.lock
        ├── pyproject.toml
        ├── src
        │   ├── gamma
        │   │   ├── BUILD
        │   │   ├── __init__.py
        │   │   └── main.py
        │   └── omega
        │       ├── BUILD
        │       ├── __init__.py
        │       └── util.py
        └── tests
            ├── BUILD
            └── test_first.py

14 directories, 25 files

Ah yes, you need to set this option to

by_source_root

Thanks! Now it all works flawlessly.

Great!