Mention if missing symbol is on the class path

[som-snytt]

Hint if there is an object in scope, in a package, which has a class, and the class path finds it.

Fixes scala/bug#12289

[som-snytt]

java.io.IOException: No space left on device

[SethTisue]

I re-ran the Jenkins build, now that the community build runs that were using all the disk have finished.

I wonder sometimes if we should have a dedicated worker behemoth just for PR validation, separate from the behemoths used for the community build.

[som-snytt]

Needs refinement, as it does add verbiage for incremental compilation error.

[error] /home/amarki/snips/test-12289/src/main/scala/c.scala:4:17: not found: type T
[error] A definition on the class path may be hidden by a source artifact. (Companions must be defined together.)

because (as will surprise no one) the class is still there, i.e., previous artifacts are not cleaned first.

./target/scala-2.13/classes/p/Main.class
./target/scala-2.13/classes/p/T.class
./target/scala-2.13/classes/p/Main$.class
./target/scala-2.13/classes/p/C.class
./target/scala-2.13/classes/p/Main$delayedInit$body.class

[som-snytt]

The clever test is tweaked to allow -d.

The output check in typer may require tweaking: it uses single output only, and compares the path strings to mean "includes".

[lrytz]

It seems a helpful addition. Given

package p {
  object T
  class C extends T
}

and

package p {
  trait T
}

I assume IntelliJ would happily navigate from extends T to the definition of trait T, which makes it harder to figure why compilation fails.

[lrytz]

This I don't immediately understand; lookup for name failed (we're about to issue an error), but lookupSymbol(name.toTermName).owner.info.decls.lookupAll(name) gives a result. How is that?

[som-snytt]

The package is loaded from class path first, which creates symbols of existing class + its module & module class. Then compilation of source takes over the existing module symbol, which is entered into scope.

It's fishy that the package class has a set of members but not all are in scope. Previously I've read a comment about stale symbols from previous run; symbol history, like human history, is a story of wreckage and detritus. Somehow I had never fully considered the state of the environment during incremental compilation.

[som-snytt]

🤯

[som-snytt]

Followed suggestions for better message, tweak test so -d /tmp never outputs, add test for the "multiple -d" case (not sure if that is used by current tooling) and handle that. Also handle shadowing of companion class or companion module, as pointed out in the review.

I agree with the previous comment that REPL's reminder that "companions must be defined together" is not optional. This synthetic shadowing is very tricky.

dotty has same behavior:

➜  scala git:(issue/12289-module-class-shadowing) scalac -d /tmp/sandbox test/files/neg/t12289/t_1.scala
➜  scala git:(issue/12289-module-class-shadowing) scalac -cp /tmp/sandbox -d /tmp/sandbox test/files/neg/t12289/c_2.scala
-- [E006] Not Found Error: test/files/neg/t12289/c_2.scala:6:18 ----------------------------------------------------------------------
6 |  class C extends T
  |                  ^
  |                  Not found: type T
  |
  | longer explanation available when compiling with `-explain`
1 error found

FSR I don't understand yet, the test under Vulpix says

-- [E006] Not Found Error: tests/neg/i20510/c_2.scala:6:18 -------------------------------------------------------------
6 |  class C extends T // error
                  ^
                  Not found: type T - did you mean T.type?

[som-snytt]

If I weren't so lazy, I'd help with why the spec build fails so often always. That was a problem in the old days, but why is it a problem in the new days?

[lrytz]

I hope this will prevent a lot of headscratching! Thanks.

[som-snytt]

Periodic reminder to get out the xpres spa scalp massager device. It's quite soothing.

[lrytz]

Some soothing might be needed because this PR broke on Windows... https://github.com/scala/scala/actions/runs/9369646735/job/25794666793

+error: /tmp does not exist or is not a directory

[lrytz]

why the spec build fails

https://travis-ci.community/t/travis-focal-ubuntu-image-uses-now-expired-mongodb-4-4-package/14293/4

[som-snytt]

Well, you warned me about /tmp. I'll follow up now.