## Summary
This just replaces one temporary solution to recursive protocols (the
`SelfReference` mechanism) with another one (track seen types when
recursively descending in `normalize` and replace recursive references
with `Any`). But this temporary solution can handle mutually-recursive
types, not just self-referential ones, and it's sufficient for the
primer ecosystem and some other projects we are testing on to no longer
stack overflow.
The follow-up here will be to properly handle these self-references
instead of replacing them with `Any`.
We will also eventually need cycle detection on more recursive-descent
type transformations and tests.
## Test Plan
Existing tests (including recursive-protocol tests) and primer.
Added mdtest for mutually-recursive protocols that stack-overflowed
before this PR.
We already had support for homogeneous tuples (`tuple[int, ...]`). This
PR extends this to also support mixed tuples (`tuple[str, str,
*tuple[int, ...], str str]`).
A mixed tuple consists of a fixed-length (possibly empty) prefix and
suffix, and a variable-length portion in the middle. Every element of
the variable-length portion must be of the same type. A homogeneous
tuple is then just a mixed tuple with an empty prefix and suffix.
The new data representation uses different Rust types for a fixed-length
(aka heterogeneous) tuple. Another option would have been to use the
`VariableLengthTuple` representation for all tuples, and to wrap the
"variable + suffix" portion in an `Option`. I don't think that would
simplify the method implementations much, though, since we would still
have a 2×2 case analysis for most of them.
One wrinkle is that the definition of the `tuple` class in the typeshed
has a single typevar, and canonically represents a homogeneous tuple.
When getting the class of a tuple instance, that means that we have to
summarize our detailed mixed tuple type information into its
"homogeneous supertype". (We were already doing this for heterogeneous
types.)
A similar thing happens when concatenating two mixed tuples: the
variable-length portion and suffix of the LHS, and the prefix and
variable-length portion of the RHS, all get unioned into the
variable-length portion of the result. The LHS prefix and RHS suffix
carry through unchanged.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
This PR closesastral-sh/ty#164.
This PR introduces a basic type narrowing mechanism for
attribute/subscript expressions.
Member accesses, int literal subscripts, string literal subscripts are
supported (same as mypy and pyright).
## Test Plan
New test cases are added to `mdtest/narrow/complex_target.md`.
---------
Co-authored-by: David Peter <mail@david-peter.de>
## Summary
This is sort of an anticlimactic resolution to #17863, but now that we
understand what the root cause for the stack overflows was, I think it's
fine to enable running on this project. See the linked ticket for the
full analysis.
closes#17863
## Test Plan
Ran lots of times locally and never observed a crash at worker thread
stack sizes > 8 MiB.
