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error during expansion of this match (this is a scalac bug)
after upgrade from 2.13.10 to 2.13.11
#12814
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error during expansion of this match (this is a scalac bug)
after upgrade from 2.13.10 to 2.13.11
Caused by scala/scala#10247 (tested by reverting it on top of current 2.13.x) |
Workaround: use the |
Canonical example: trait A[X] { type T = X }
object B extends A[String]
object C extends A[B.T] {
def f: C.T = "hai"
} The problem is in |
It needs a label In addition, of course, having a workaround (of some sort) mitigates the need for a fix (which may cause revertible effects in turn). And perhaps a more optimal fix will be forthcoming than could be achieved by the next release. A regression has an urgency attached to it that drags upon any alleviation. "Haste makes waste." |
@abebeos I was suggesting why "regression" is not appropriate. You may disagree, of course. Such is the open in open source. |
@abebeos there is no such protocol. I was trying to answer your question so Lukas wouldn't have to. You are free to be dissatisfied with my answer on its merits, of course. Either Lukas made a mistake in removing the regression label, or he was not mistaken but you are asking to prioritize this issue. |
It's the canonical example in the sense that it shows the underlying problem, which indeed has been around for a long time (also 2.12). My example fails in the type checking phase. The example given in this ticket fails in a later phase (patmat) which generates code similar to my example and then fails to type check it. So the change in patmat (scala/scala#10247) exposed the underlying issue in a new way, it did not cause it. That's why I removed the "regression" label, but one can argue either way. |
It seems @retronym has a branch for it: #8252 (comment) (haven't looked, but it seems that). |
The following code causes compilation error under 2.13.11
File
bug.sc
Run with:
Compiler error:
It was not the case under 2.13.10, where code compiles successfully.
Run under 2.13.10, change the first line to
//> using scala "2.13.10"
and run as before
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