InstallRequirement only checks for a delete marker file in source_dir.
Since the result of ensure_build_location is set to source_dir (in
ensure_has_source_dir), and ensure_build_location returns a subdirectory
of the build_directory to which we write the delete marker file, then
this delete marker file is never used.
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.
_should_cache is only called by _get_cache_dir.
In pip install mode, _get_cache_dir is never called when
check_binary_allowed returns False because in that case
should_build_for_install_command has returned False before
and the build was skipped.
In pip wheel mode, check_binary_allowed always returns True
(because it is not passed to the build function).
So _should_cache can use _always_true for check_binary_allowed.
*Alternative*
Alternatively, we could have passed check_binary_allowed
to build in pip wheel mode. The only difference is that wheels built
locally from *legacy* packages would then not be cached,
when pip wheel is used with --no-binary.
This gives us a global toggle that we can use to control whether
temporary directories get deleted from one place (ideally, in the
commands taking --no-clean).
This untested function was only used in one place. Inlining it makes it
easier to see the symmetry between the writing of the delete marker file
in `ensure_build_location` and checking for it in
`remove_temporary_source`.
req.source_dir is only set by:
1. `InstallRequirement.__init__`
2. `InstallRequirement.ensure_has_source_dir`
`InstallRequirement.__init__` is only called with source_dir for
editable requirements, for which we would not call
`RequirementPreparer.prepare_linked_requirement` (only
`prepare_editable_requirement`).
We will use this assertion for justifying later refactoring.
Previously, these were used when the user did not provide an explicit
ABI. Now this is handled internally in `packaging.tags` (by
`_cpython_abi` and `_generic_abi`).
Since we only call this function when platform is not None, we can drop
one of the branches. This is the only place using our manylinux
auto-deduction functions, so those can be removed next.
Now that we're fully using packaging.tags, everything in the supported
list is already Tag.
Further, since each function is responsible for its own set of
non-overlapping tags, we can also remove the de-duplication.
