When performing `install --dry-run` and PEP 658 .metadata files are
available to guide the resolve, do not download the associated wheels.
Rather use the distribution information directly from the .metadata
files when reporting the results on the CLI and in the --report file.
- describe the new --dry-run behavior
- finalize linked requirements immediately after resolve
- introduce is_concrete
- funnel InstalledDistribution through _get_prepared_distribution() too
The typing module has been available since Python 3.5. Guarding the
import has been unnecessary since dropping Python 2.
Some guards remain to either:
- Avoid circular imports
- Importing objects that are also guarded by typing.TYPE_CHECKING
- Avoid mypy_extensions dependency
The stdlib module has been available since Python 3.5 and the
TYPE_CHECKING constant has been available since 3.5.2.
By using stdlib, this removes the need for pip to maintain its own
Python 2 typing compatibility shim.
Certain environments seem to be leaving behind empty folders in this
directory -- There was an older pip release that included a source/
folder here which isn't getting deleted for some reason. I have not
figured out the root cause why this happens yet. This is resulting in
ImportErrors since Python imports have a higher precedence for packages
compared to modules.
This commit changes the name we're trying to import from, which should
help prevent this mode of failure.
Why: Based on some more experience from refactoring metadata generation,
it became clear to me that the separation of legacy vs modern codepaths
should happen at lower level than this abstraction.
This moves the DistAbstraction logic into a dedicated 'distributions'
sub-package, with separated modules for the concrete implementations of
various distribution handling logic.
