Absolute paths in ._trace files when building with maven and xtext-maven-plugin

[LorenzoBettini]

See https://bugs.eclipse.org/bugs/show_bug.cgi?id=503309

[szarnekow]

Here we install a project config on the resource set
https://github.com/eclipse/xtext/blob/main/org.eclipse.xtend.core/src/org/eclipse/xtend/core/compiler/batch/XtendBatchCompiler.java#L412

That project config has enough information to provide source folders and the like - which allows to create a project relative path to the source file.

In the maven plugin, we should probably configure a proper project configuration provider that exposes the source folders etc to the languages, too.

https://github.com/eclipse/xtext/blob/main/org.eclipse.xtext.maven.plugin/src/main/java/org/eclipse/xtext/maven/AbstractXtextGeneratorMojo.java#L187

[LorenzoBettini]

further hint: see what the org.eclipse.xtext.xbase.testing.CompilationTestHelper.resourceSet(Pair<String, ? extends CharSequence>...) does:

	public ResourceSet resourceSet(@SuppressWarnings("unchecked") Pair<String,? extends CharSequence> ...resources ) throws IOException {
		XtextResourceSet result = newResourceSetWithUTF8Encoding();
		FileProjectConfig projectConfig = new FileProjectConfig(new File(workspaceRoot,PROJECT_NAME), PROJECT_NAME);
		projectConfig.addSourceFolder("src");
		ProjectConfigAdapter.install(result, projectConfig);
		for (Pair<String, ? extends CharSequence> entry : resources) {
			URI uri = copyToWorkspace(getSourceFolderPath()+"/"+entry.getKey(), entry.getValue());
			Resource resource = result.createResource(uri);
			if (resource == null)
				throw new IllegalStateException("Couldn't create resource for URI "+uri+". Resource.Factory not registered?");
			resource.load(result.getLoadOptions());
		}
		return result;
	}

[LorenzoBettini]

@szarnekow Do you think this could be done/addressed directly in the StandaloneBuilder when we pass the sources?