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Fix Dependent types in TupledFunction #23615
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Fix Dependent types in TupledFunction #23615
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Ok I did locally fix that test, but now I made a new test to make sure that It can untuple dependent types, and I seemed to have found a bug in inference? Inference also discards dependent types:
object Test {
def main(args: Array[String]): Unit = {
val f2: (x: (Int, Long)) => x._1.type = (args: (Int, Long)) => args._1
val g2: (x: Int, y: Long) => x.type = f2.untupled
println(g2(1, 3L))
}
extension [F, Args <: Tuple, R](f: Args => R) def untupled(using tf: TupledFunction[F, Args => R]): F = tf.untupled(f)
}
-- [E008] Not Found Error: tests/run/i21808.scala:8:45 -----------------------------------------------------------------
8 | val g2: (x: Int, y: Long) => x.type = f2.untupled
| ^^^^^^^^^^^
|value untupled is not a member of (x: (scala.Int, scala.Long)) => (x._1 : scala.Int).
|An extension method was tried, but could not be fully constructed:
Compiler SHOULD try to fill in [F, X <: (Int, Long), X._1] (or however its correctly written out) but instead tries to construct
[F, (scala.Int, scala.Long), scala.Int]
and the compiler (correctly) rejects the attempt to untuple a dependent type into a non-dependent type
The case where the left side isn't a function type/ is a type param now works for non dependent type cases. HOWEVER, now the compiler rejects constructions like `untupled` for dependent types, when it should accept them. [skip community_build] [skip docs] [skip test_windows_fast] [skip mima]
Remove the new test as it seems to be a different, unrelated issue [skip community_build] [skip docs] [skip test_windows_fast] [skip mima]
new code is incorrect,
summon[TupledFunction[(x: T, y: T) => x.type, (x: (T, T)) => Tuple.Elem[x.type, 0]]] fails to compile due to a match error.
A large issue is that there is no good "standard" for selecting elements of tuples in scala. TupledFunction treats tuples specially and I feel like the compiler should definitely have more control over them, instead of relegating them to the stdlib. However, I don't really know of a good way to fix this
Try to fix #21808
I NEED HELP! PLEASE HELP ME! I'VE NEVER DONE COMPILER STUFF BEFORE!
Current progress:
Fixed the bug, but now "tests/run/tupled-function-untupled" fails, probably because i updated the code incorrectly
YES, this code is a mess. I DONT KNOW HOW THE COMPILER WORKS! This is also a draft so I can get guidance on how to do this work properly.