StandardLocation.PATCH_MODULE_PATH unsupported by javax.tools.JavaCompiler?

[Martin Desruisseaux]

Hello

I'm rewriting the Maven compiler plugin for better support of Java 
Module System with Maven 4 [1]. This work removes completely the Plexus 
compiler API and uses directly the `javax.tools.JavaCompiler` interface 
instead. It works well, but I'm having an issue with the 
`--patch-module` option (for compiling the tests of modular projects). 
My understanding is that the modules to patch should be specified by a 
code like below:

    JavaCompiler compiler = ...;
    try (StandardJavaFileManager fm = getStandardFileManager(...)) {
         String module = ...;
         List<Path> testSources = List.of(...); // A single directory
         fm.setLocationForModule(StandardLocation.PATCH_MODULE_PATH, module, testSources);
    }

However, it results in an UnsupportedOperationException thrown by 
`com.sun.tools.javac.file.Locations.PatchModulesLocationHandler`. The 
source code is as below:

    @Override // defined by LocationHandler
    void setPathsForModule(String moduleName, Iterable<? extends Path> files) throws IOException {
         throw new UnsupportedOperationException(); // not yet
    }

The "not yet" comment gives the impression that this method is intended 
to be implemented, is that right? A workaround is to put 
`--patch-module` in the options passed as the `options` argument in the 
call to `JavaCompiler.getTask(...)`. But a call to 
`compiler.isSupportedOption("--patch-module")` returns -1, meaning that 
it should not be allowed. I noticed that if I ignore this information 
and put a `--patch-module` option anyway, it works. But isn't it a 
violation of JavaCompiler API contract? The Javadoc said that it should 
throw IllegalArgumentException if any option is invalid.

Thanks,

     Martin

[1]https://github.com/Geomatys/maven-compiler-plugin/wiki
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/compiler-dev/attachments/20240729/9b136a55/attachment.htm>