Regression: "Cannot build interface type for term" crash during compilation #61192
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stephencelis
added
the
bug
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@slavapestov This may be in your wheelhouse? |
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I worked around the problem by replacing the With where Bytes == Parsers.MapConversion<Parsers.ReplaceError<Rest<Data>>, C> { |
AnthonyLatsis
added
compiler crash
generics
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Nice, I was about to suggest the same workaround but you beat me to it. Here is a reduced test case: struct Data {}
protocol Parser {
associatedtype Input
}
struct Rest<Input>: Parser {}
struct Body<Bytes: Parser> where Bytes.Input == Data {
init<C: Parser>(_: C) where Bytes == Rest<Bytes.Input>, C.Input == Bytes.Input {}
} |
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The problem is that the requirement |
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The regression was introduced by #60507, but it's exposing an existing bug which needs to be fixed in a more fundamental way. |
slavapestov
added a commit
to slavapestov/swift
that referenced
this issue
Sep 20, 2022
…e equivalence classes
This fixes an edge case where we start with the following requirements:
- U : P
- T : P
- T.[P]A == C
- T == G<T.[P]A>
- U.[P]A == T.[P]A
and end up with the following set of minimal rules (where the type
witness for [P]A in the conformance G<C> : P is C):
- U.[P] => U
- U.[P:A] => T.[P:A]
- T.[concrete: G<C>] => T
- T.[concrete: G<C> : P] => T
Since U.[P]A and T.[P]A are concrete, we split the abstract same-type
requirement into two requirements, and re-run minimization:
- U : P
- T.[P]A == C
- U.[P]A == C
- T == G<C>
The concrete conformance rule T.[concrete: G<C> : P] => T does not
correspond to a requirement, so it was simply dropped, and the above
rules violate post-contraction invariants; T.[P]A is not a valid
type parameter because there is no conformance requirement T : P in
the minimized signature.
We can fix this by re-running concrete contraction after splitting
concrete equivalence classes. After contraction, the above requirements
turn into
- U : P
- C == C
- U.[P]A == C
- T == G<C>
Which correctly minimizes to
- U : P
- U.[P]A == C
- T == G<C>
Both concrete contraction and concrete equivalence classes are hacks,
and we should think of a way to directly express the transformations
they perform with the rewrite system.
Fixes swiftlang#61192.
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swift-url-routing no longer crashes when built with my fix. |
AnthonyLatsis
added
crash
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Describe the bug
A project that built fine in Xcode 14.0 crashes during compilation in Xcode 14.1.
Steps To Reproduce
Steps to reproduce the behavior:
Clone the repo and check out the affected tag:
git clone https://github.com/pointfreeco/swift-url-routing cd swift-url-routing git checkout 0.3.0Open in Xcode 14.1.
Build the
URLRoutingtarget.Expected behavior
It builds.
Actual behavior
Screenshots
If applicable, add screenshots to help explain your problem.
Environment (please fill out the following information)
Additional context
Related: pointfreeco/swift-url-routing#52
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