Regression: "Cannot build interface type for term" crash during compilation #61192
Comments
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 https://github.com/pointfreeco/swift-url-routing/blob/0.3.0/Sources/URLRouting/Body.swift#L29 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. |
…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
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
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Environment (please fill out the following information)
Additional context
Related: pointfreeco/swift-url-routing#52
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