[GROOVY-8439] @CompileStatic cannot compile generic class's static method

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 2.4.12
• Fix Version/s: 3.0.0-alpha-2, 2.5.0-rc-1, 2.4.15, 2.6.0-alpha-4
• Component/s: Static compilation
• Environment: Windows 10, Gradle 4.2.1; ; IRL @CompileStatic applied via groovyOptions.configurationScript: ; withConfig(configuration) { ast(groovy.transform.CompileStatic) }
• Assignee: Daniel Sun
• Reporter: Robert Papp
• Created: 10/Jan/18 00:20
• Updated: 10/Apr/18 13:02
• Resolved: 10/Mar/18 15:08

Description

Below code is a simplification of a Gradle API + Android Gradle Plugin consuming code:

@CompileStatic
class Test<T extends Task> {

	static def something(Task task, Collection<BaseVariant> variants) {
		variants
				.collectMany {it.sourceFolders}
				.collect {ConfigurableFileTree tree ->
			task.buildDir.toPath().relativize(tree.dir.toPath()).toString() + File.separator
		}
	}
}

interface BaseVariant {

	List<ConfigurableFileTree> getSourceFolders()
}

interface ConfigurableFileTree {

	File getDir()
}

interface Task {

	File getBuildDir()
}

Removing <T extends Task> makes it compile, otherwise:

test\src\main\groovy\Test.groovy: 8: Expected parameter of type Task but got ConfigurableFileTree
 @ line 8, column 15.
   				.collect {ConfigurableFileTree tree ->
                 ^

test\src\main\groovy\Test.groovy: 9: [Static type checking] - No such property: dir for class: Task
 @ line 9, column 38.
   			task.buildDir.toPath().relativize(tree.dir.toPath()).toString() + File.separator
                                        ^

test\src\main\groovy\Test.groovy: 9: [Static type checking] - Cannot find matching method java.nio.file.Path#relativize(java.lang.Object). Please check if the declared type is right and if the method exists.
 @ line 9, column 4.
   			task.buildDir.toPath().relativize(tree.dir.toPath()).toString() + File.separator
      ^

3 errors

:checkstyle:compileGroovy FAILED

So far I haven't found a workaround other than removing generics!