New semantic analyzer: Refactor handling of is_inferred_def & co #6458
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refactoring
Changing mypy's internals
semantic-analyzer
Problems that happen during semantic analysis
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ilevkivskyi
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This was referenced Feb 21, 2019
ilevkivskyi
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Jun 13, 2019
#6988) This is (kind of) an actual fix for #6952 The problem is that previously `unwrap_final()` unconditionally set `s.type` to `None` for bare `Final`, even if the type was inferred from a simple literal r.h.s. on a previous iteration. At the same time `lvalue.is_inferred_def` remained `False`, so that the type was not inferred on the second iteration. This way `s.type` and `lvalue.is_inferred_def` may get out of sync depending on the number of iterations, thus causing weird behavior in type checker. I generally can say the current way of storing the inferred status is error-prone, but we already have #6458 to track this.
PattenR
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Jun 23, 2019
python#6988) This is (kind of) an actual fix for python#6952 The problem is that previously `unwrap_final()` unconditionally set `s.type` to `None` for bare `Final`, even if the type was inferred from a simple literal r.h.s. on a previous iteration. At the same time `lvalue.is_inferred_def` remained `False`, so that the type was not inferred on the second iteration. This way `s.type` and `lvalue.is_inferred_def` may get out of sync depending on the number of iterations, thus causing weird behavior in type checker. I generally can say the current way of storing the inferred status is error-prone, but we already have python#6458 to track this.
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There are several things that hold information about whether a type of variable should be inferred or not:
RefExpr.is_new_defRefExpr.is_inferred_defVar.is_readyVar.is_inferredTypeChecker.is_definition()Such a variety of things is partially caused by the fact that special definitions like named tuples etc. used to have a
Var()to which thelvaluewas pointing. With the new analyzer we don't have this, so it would be good to clean-up/refactor the logic around inference after we merge the two analyzers.See also #6453
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