bad option '-target:16' was ignored when compiling scala code with Scala3 library

[Kotori316]

'16' means Java 16.
The option passed to scala3 compiler contains invalid argument, '-target'

Expected Behavior

'-target:16' should be '-Xtarget:16', as described in here

Current Behavior

'-target:16' is passed to scala compiler and causes warning

Context

In scala 2.13.x, '-target:' option is valid. In scala3, the option is replaced to '-Xtarget:'(https://docs.scala-lang.org/scala3/guides/migration/options-lookup.html).

The option which will be passed to scala compiler is created in these codes.

gradle/subprojects/scala/src/main/java/org/gradle/api/internal/tasks/scala/ZincScalaCompiler.java

Lines 106 to 111 in 4f9c0e1

	CompileOptions compileOptions = CompileOptions.create()
	.withSources(Iterables.toArray(spec.getSourceFiles(), File.class))
	.withClasspath(classpath)
	.withScalacOptions(scalacOptions.toArray(new String[0]))
	.withClassesDirectory(spec.getDestinationDir())
	.withJavacOptions(javacOptions.toArray(new String[0]));

(#19864 seems to change code in ZincScalaCompiler but this issue may not be solved.)

The last withJavacOptions seems to add '-target:16' because it should be passed to javac, but '-target:16' is no longer valid option in scala3.

If you set other parameters such as -Wconf:cat=deprecation:w,any:e, the warning changes to an error and the compilation fails.

Steps to Reproduce

1. Add Scala 3 to dependency. implementation(group: 'org.scala-lang', name: 'scala3-library_3', version: '3.1.2-RC2')
2. Set Java version with java.toolchain.languageVersion = JavaLanguageVersion.of(16). In my code, I use Java 16 but the version does not matter.
   1. This issue also reproduced with sourceCompatibility = targetCompatibility = JavaVersion.VERSION_16

repo: https://github.com/Kotori316/gradle-issue-scala-option

Your Environment

• Gradle: 7.4.1
• Scala 3.1.2-RC2
• Java 16
• Windows 10

[vlushn]

Scala 2.13.9 also deprecates the -target option (the correct one is -release now): scala/scala#9982

Workaround for the warning is to silence it by passing "-Wconf:msg=-target is deprecated:silent"

[ljacomet]

This has been fixed in Gradle 8.0