Resolve name when named imp is behind wild imps #21888
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When a named import (such as `import bug.util.List`) is defined before two clashing wildcard imports (`import bug.util.*; import java.util.*`) the name "List" should resolve to it, rather than a resolution error being emitted. This was due to the fact that `findRefRecur` didn't return the precedence at which it found that import, `checkImportAlternatives` used the `prevPrec` to `checkNewOrShadowed`. Now we check against the entire `foundResult`, allowing an early named import to be picked over later wildcard imports.
odersky
requested changes
Nov 17, 2024
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The boxing is a heavy price to pay here. I am worried that we make findRefRecur slower for a niche case which is what #18529 is. It's trivially fixed by moving the named import behind the two wildcard imports. And the error message is informative enough to suggest something like that.
What we could do: If we get an ambiguity, try a targeted action to see whether we get a
named import in the same import sequence that would resolve the problem. That can be done without changing the signature of findRefRecur.
| @@ -238,38 +238,40 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer | |||
| !owner.isEmptyPackage || ctx.owner.enclosingPackageClass.isEmptyPackage | |||
| } | |||
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| import BindingPrec.* | |||
| type Result = (Type, BindingPrec) | |||
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I don't think we should use a boxed type here. findRefRecur is very hot, we should avoid allocating where we can.
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When a named import (such as
import bug.util.List) is defined beforetwo clashing wildcard imports (
import bug.util.*; import java.util.*)the name "List" should resolve to it, rather than a resolution error
being emitted.
This was due to the fact that
findRefRecurdidn't return theprecedence at which it found that import,
checkImportAlternativesusedthe
prevPrectocheckNewOrShadowed. Now we check against the entirefoundResult, allowing an early named import to be picked over laterwildcard imports.
Fixes #18529
(Replaces #21871)