mirror of https://github.com/pypa/pip
d45541c8f3
This is done by catching InstallationError from the underlying distribution preparation logic. There are three cases to catch: 1. Candidates from indexes. These are simply ignored since we can potentially satisfy the requirement with other candidates. 2. Candidates from URLs with a dist name (PEP 508 or #egg=). A new UnsatisfiableRequirement class is introduced to represent this; it is like an ExplicitRequirement without an underlying candidate. As the name suggests, an instance of this can never be satisfied, and will cause eventual backtracking. 3. Candidates from URLs without a dist name. This is only possible for top-level user requirements, and no recourse is possible for them. So we error out eagerly. The InstallationError raised during distribution preparation is cached in the factory, like successfully prepared candidates, since we don't want to repeatedly try to build a candidate if we already know it'd fail. Plus pip's preparation logic also does not allow packages to be built multiple times anyway. |
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conftest.py |