Can't use -release:8 with JDK8: 8 is not a valid choice for -release

[arixmkii]

Compiler version

3.1.0

Minimized code

Bash script showing issue with scalac

~ % java -version
openjdk version "1.8.0_302"
OpenJDK Runtime Environment (Temurin)(build 1.8.0_302-b08)
OpenJDK 64-Bit Server VM (Temurin)(build 25.302-b08, mixed mode)
~ % scalac -version
Scala compiler version 3.1.0 -- Copyright 2002-2021, LAMP/EPFL
~ % scalac -release:8 -help
8 is not a valid choice for -release
  scalac -help  gives more information

Output

8 is not a valid choice for -release

Expectation

Should accept the setting as this one should be safe to use.

[arixmkii]

PR provided.

[prolativ]

scalac -release 8 for scala 2.13 on JDK 8 complains with scalac error: -release is only supported on Java 9 and higher. But personally I would be ok with not raising an error in this situation. @smarter which behaviour do you think would be better?

[smarter]

Yeah I think not raising an error is better.

[arixmkii]

With scala 2.13 there was -target:jvm-1.8, which could be used. With scala 3 we only have -release option and there is no easy way to use it with builds being tested through JDK matrix of all LTS releases (you need to conditionally remove the option in sbt, when it runs on JDK 8).

[prolativ]

As mentioned in the linked zio PR, there's -Xtarget 8 which is direct replacement for older -target:jvm-1.8

[smarter]

Right but we should encourage people to use -release instead since it ensures you don't use new jdk APIs (that's why we renamed target to Xtarget)