Union and intersection types are not causing checking the kind of type parameters #16696
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bertlebee
added
itype:bug
itype:crash
stat:needs triage
This was referenced Jan 14, 2023
Kordyjan
added
area:typer
stat:needs minimization
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Self-contained example: class Box[R]
class BoxMaker[T] {
def make[R <: T](f: T => Box[R]): Box[R & T] = ???
}
trait Foo[A]{
def foo: Box[Foo[Unit]]
}
val boom = BoxMaker[Foo/*[Unit]*/].make(_.foo)Uncommenting |
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It still crashes on the current nightly and has been crashing since 3.0.0. |
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I've played a bit with it and was able to minimise it to just: class BoxMaker[T] {
def make: T & Int = ???
}
val boom = BoxMaker[Some].makeIf we use union type instead of intersection, it also crashes similarly. class BoxMaker[T] {
def make: T | Int = ???
}
val boom = BoxMaker[Some].makeIt seems that intersections and unions are not enforcing kinds of type parameters. |
Kordyjan
changed the title
odersky
added a commit
to dotty-staging/dotty
that referenced
this issue
Jan 17, 2023
Throw a type error instead of crashing when using higher-kinded types in unions or intersections. We check kindedness only in PostTyper (to avoid cycles), which means we might get into situations where we coming a higher-kinded type in a union or intersection, which is illegal. In this case we now diagnose the problem with a TypeError instead of failing an assert. However, after Typer we do fail since by then such situations should have been checked by then. Fixeds scala#16696
odersky
added a commit
that referenced
this issue
Jan 18, 2023
…6712) Throw a type error instead of crashing when using higher-kinded types in unions or intersections. We check kindedness only in PostTyper (to avoid cycles), which means we might get into situations where we combine a higher-kinded type in a union or intersection, which is illegal. In this case we now diagnose the problem with a TypeError instead of failing an assert. However, after Typer we do fail since by then such situations should have been checked by then. Fixes #16696
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Wow, thanks for getting all of these sorted for me! |
little-inferno
pushed a commit
to little-inferno/dotty
that referenced
this issue
Jan 25, 2023
Throw a type error instead of crashing when using higher-kinded types in unions or intersections. We check kindedness only in PostTyper (to avoid cycles), which means we might get into situations where we coming a higher-kinded type in a union or intersection, which is illegal. In this case we now diagnose the problem with a TypeError instead of failing an assert. However, after Typer we do fail since by then such situations should have been checked by then. Fixeds scala#16696
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Compiler version
3.2.1
Minimized code
https://scastie.scala-lang.org/VEozYp5OQlmLyTb0hn3KQw
Output (click arrow to expand)
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