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Assuming you want to compile an Error Prone custom check (https://github.com/tbroyer/gradle-errorprone-plugin/issues/93), and looking at how Error Prone itself is compiled (https://github.com/google/error-prone/blob/ae3a19f44e173847d5e01bc95fd0b1d74a41d6b6/pom.xml#L181-L206), you'll want to use those 12 add-exports to your

compilerArgs

, and add the add-opens and add-exports from https://errorprone.info/docs/installation (or https://github.com/google/error-prone/blob/ae3a19f44e173847d5e01bc95fd0b1d74a41d6b6/pom.xml#L235-L257) to the

jvmArgs

of your test and exec tasks.

Thanks Thomas for the quick response, when I try to add-exports, I get this:

error: exporting a package from system module jdk.compiler is not allowed with --release

I have a pretty standard build configuration, is there anything else I shoudl modify?

Ah, I think you cannot use toolchains (IIRC), and must use `sourceCompatibility`/`targetCompatibility` (and specifically not

release

) to define Java compatibility.

Is using toolchain really adding

release

if not explicitly setting it? I'd assumed that due to the proper toolchain being used already,

release

should not be necessary.

@Vampire I do use toolchain, this is my only configuration

JavaPluginExtension javaExt = (JavaPluginExtension) project.getExtensions().getByName("java");

javaExt.getToolchain().getLanguageVersion().set(JavaLanguageVersion.of(11));

Yeah, just testing also. Seems you even cannot prevent it using

tasks.compileJava { options.release.set(provider { null }) }

😞 You can only override it to something else. So it indeed seems to be not possible to use something that is incompatible with

--release

with toolchains, except with some trickery like

tasks.compileJava {
    javaCompiler.set(provider { null })
    options.forkOptions.javaHome = javaToolchains.compilerFor(java.toolchain).get().metadata.installationPath.asFile
}

So, @Vampire, should I refrain from using toolchain and use source and target compatability instead?

Assuming @Thomas Broyer is correct regarding

-release

being the problem, I would probably use what I posted last + defining compatibility on the task. Then other tasks can continue using the defined toolchain and also the computer task is using the toolchain, just in a custom way, so you preserve the separation of Java to run Gradle and the Java to build your project. It might also be worth submitting a bug or feature request for being able to not use

-release

with normal toolchain usage, as you have a valid use-case for it.