mirror of https://github.com/astral-sh/ruff
97935518e9
This patch lets us create specializations from a constraint set. The constraint encodes the restrictions on which types each typevar can specialize to. Given a generic context and a constraint set, we iterate through all of the generic context's typevars. For each typevar, we abstract the constraint set so that it only mentions the typevar in question (propagating derived facts if needed). We then find the "best representative type" for the typevar given the abstracted constraint set. When considering the BDD structure of the abstracted constraint set, each path from the BDD root to the `true` terminal represents one way that the constraint set can be satisfied. (This is also one of the clauses in the DNF representation of the constraint set's boolean formula.) Each of those paths is the conjunction of the individual constraints of each internal node that we traverse as we walk that path, giving a single lower/upper bound for the path. We use the upper bound as the "best" (i.e. "closest to `object`") type for that path. If there are multiple paths in the BDD, they technically represent independent possible specializations. If there's a single specialization that satisfies all of them, we will return that as the specialization. If not, then the constraint set is ambiguous. (This happens most often with constrained typevars.) We could in the future turn _each_ of the paths into separate specializations, but it's not clear what we would do with that, so instead we just report the ambiguity as a specialization failure. |
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| README.md | ||
| ty_extensions.pyi | ||
README.md
The build.rs copies the ty_extensions.pyi file in this directory into
the vendor/typeshed/stdlib directory.