Feature request: improve detection of scala compiler

[oharboe]

I'm using Bloop with bazel and I'm running into a snag wit the detection of the Scala compiler.

The long story short is that the scala-compiler file recognition fails because the file name is changed to processed_scala-compiler-2.13.16.jar:

Caused by: java.lang.RuntimeException: Missing compiler jar in Scala jars /home/oyvind/bazel-orfs/bazel-out/k8-opt-exec-ST-d57f47055a04/bin/external/rules_jvm_external++maven+maven/org/scala-lang/scala-compiler/2.13.16/processed_scala-compiler-2.13.16.jar, ...

bloop/backend/src/main/scala/bloop/ScalaInstance.scala

Lines 73 to 75 in b90aaa8

	private def hasScalaCompilerName(filename: String): Boolean =
	filename.startsWith(ScalacCompilerName) ||
	(isDotty && (filename.startsWith("dotty-compiler") || filename.startsWith("scala3-compiler")))

Feature request: make compiler detection a bit more flexible or change it to a warning so that processed_ prefixes doesn't stop it from working.

[oharboe]

Workaround, add this to .bazelrc:

# Stamping the manifest changes the name of `scala-compiler-2.13.16.jar` to
# `processed_scala-compiler-2.13.16.jar`, which keeps `bloop` from recognizing
# it.
# Read more:
# https://web.archive.org/web/20250624074624/https://github.com/scalacenter/bloop/blob/b90aaa82e0799b8783b1812f4c07961d4c47ec30/backend/src/main/scala/bloop/ScalaInstance.scala#L73-L75
# https://web.archive.org/web/20250624074941/https://github.com/bazel-contrib/rules_jvm_external/issues/786
common --@rules_jvm_external//settings:stamp_manifest=false

[tgodzik]

Thanks for reporting! We need to provide Zinc with an actual compiler jar, so we need a way to find it based on the classpath we are getting.

Feature request: make compiler detection a bit more flexible or change it to a warning so that processed_ prefixes doesn't stop it from working.

A warining would not do, but we can also account for the prefix, would that be ok for you?

[oharboe]

Thanks for reporting! We need to provide Zinc with an actual compiler jar, so we need a way to find it based on the classpath we are getting.

Feature request: make compiler detection a bit more flexible or change it to a warning so that processed_ prefixes doesn't stop it from working.

A warining would not do, but we can also account for the prefix, would that be ok for you?

How about using a regex?

.*scala-compiler.jar

[tgodzik]

Would #2715 work for you?