Fix #1457: Three incompatbilities with scalac #1465
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Two of these are unavoidable. I moved the tests to diabled/not-representable and added in each case a comment to the main scala file detailing why there is a deviation. The last one (import-rewrite) is fixed.
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LGTM. Would be interesting to know how much code in the wild will be affected by these differences. |
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@olafurpg Yes, let's talk about how to bridge the gap here. I believe the rewriting tool and/or the scala compiler could at least give warnings for cases like these which are not representable. We might also be able to handle the "naming-resolution" problem specially in scala2mode. |
Scala2 does not conform to spec Section 2, where it says:
Bindings of different kinds have a precedence defined on them:
1. Definitions and declarations that are local, inherited, or made available by a package clause and also defined in the same compilation unit as the reference, have highest precedence.
2. Explicit imports have next highest precedence.
3. Wildcard imports have next highest precedence.
4. Definitions made available by a package clause, but not also defined in the same compilation unit as the reference, have lowest precedence.
In fact Scala 2, merges (1) and (4) into highest precedence.
This commit simulates the Scala2 behavior under -language:Scala2, but gives a migration
warning. For the naming-resolution test case we get:
dotc *.scala -language:Scala2 -migration
callsite.scala:9: migration warning: Name resolution will change.
currently selected : naming.resolution.Files
in the future, without -language:Scala2: java.nio.file.Files'
where Files is a type in package object package which is an alias of java.util.stream.Stream[java.nio.file.Path]
Files' is a class in package file
def gimmeFiles: Files = Files.list(Paths.get("."))
^
one warning found
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The naming resolution case is now supported under -language:Scala2, and gives a migration warning. There's still nothing we can do about the hkt case. |
Three goals:
1. Fix crasher in compileStdLib by saving and restoring
foundUnderScala2 analogous to iportedFromRoot.
2. Make behavior the same as scalac under Scala2 mode -
ListBuffer behaved differently before.
3. Make findRef faster by making it tail-recursive
as long as nothing was found.
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Two of these are unavoidable. I moved the tests to diabled/not-representable
and added in each case a comment to the main scala file detailing why there
is a deviation.
The last one (import-rewrite) is fixed.
review by @olafurpg