Change/type aliases #270
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Change/type aliases #270
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Curiously, was missing before, which meant variance was ignored when hash-consing TypeBounds.
Specialize hash consing of type aliases.
Replace all
case TypeBounds(lo, hi) if lo eq hi =>
patterns with
case TypeAlias(alias) =>
So far this affects only the calls, both methods are still the same. But their implementation will be changed next.
Generate Type aliases only when original type(s) were aliases. Also, TypeBounds.real never generates an alias.
TypeBounds.real served its purpose: Flushing out all problems with creating TypeBounds.
This was the last bit that tested for the fragile `lo eq hi` condition.
| override def variance = 1 | ||
| override def toString = "Co" + super.toString | ||
| abstract class TypeAlias(val alias: Type, override val variance: Int) extends TypeBounds(alias, alias) { | ||
| /** pre: this is a type alias */ |
|
Anyone else wants to have a look at this? |
|
Going to merge this one now. |
tgodzik
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Apr 29, 2025
Backport "Regression test for extension nullification, nowarn for different opacities" to 3.3 LTS
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Avoid identifying type aliases as TypeBounds where the lower and upper bound are
eq. Thisis too fragile, in particular it might have false positives for type aliases, which go the other way when
compiling in a second run.
I tried to identify a type alias as a type where the bounds are
=:=. But this gave CyclicReferenceerrors which seemed very hard to avoid. So the new scheme is different. TypeAliases are explicitly
created.
Review by @DarkDimius