Charset used to compile the grammar is system default, not UTF-8

[hakanai]

I was using the following configuration:

val generateKotlinGrammarSource by tasks.registering(AntlrKotlinTask::class) {
    antlrClasspath = configurations.detachedConfiguration(
        project.dependencies.create("com.strumenta.antlr-kotlin:antlr-kotlin-target:ebf3caf7ff")
    )

    source = project.objects
        .sourceDirectorySet("antlr", "antlr")
        .srcDir("src/main/antlr").apply {
            include("**/*.g4")
        }
    outputDirectory = file("$buildDir/generated-src/antlr/main/kotlin")
}

The grammar appeared to compile fine, but then rules using Unicode inside my .g4 file were not passing the tests.

It turned out I had to manually set the encoding:

val generateKotlinGrammarSource by tasks.registering(AntlrKotlinTask::class) {
    arguments = arguments + listOf("-encoding", "UTF-8")
    // ...
}

It's 2022; I think UTF-8 can be the default by now and we shouldn't be forcing every project to set this themselves.