[#2464] Fix picocli-codegen module-info missing provides for annotation processor

picocli-codegen-tests-java9plus/src/test/java/picocli/annotation/processing/tests/Issue2464Test.java

@@ -0,0 +1,83 @@
+package picocli.annotation.processing.tests;
+
+import org.junit.Test;
+import picocli.codegen.aot.graalvm.processor.NativeImageConfigGeneratorProcessor;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.lang.module.ModuleDescriptor;
+import java.lang.module.ModuleFinder;
+import java.lang.module.ModuleReference;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+/**
+ * Ensures {@code info.picocli.codegen} declares a {@code provides ... with}
+ * for {@link javax.annotation.processing.Processor} so the annotation processor
+ * is discovered when placed on {@code --processor-module-path}.
+ *
+ * @see <a href="https://github.com/remkop/picocli/issues/2464">#2464</a>
+ */
+public class Issue2464Test {
+
+    private static final String MODULE_NAME = "info.picocli.codegen";
+    private static final String PROCESSOR_SERVICE = "javax.annotation.processing.Processor";
+    private static final String PROCESSOR_IMPL =
+            "picocli.codegen.aot.graalvm.processor.NativeImageConfigGeneratorProcessor";
+
+    @Test
+    public void moduleInfoProvidesAnnotationProcessor() throws Exception {
+        ModuleDescriptor descriptor = readCodegenModuleDescriptor();
+        assertEquals(MODULE_NAME, descriptor.name());
+
+        Set<String> providers = descriptor.provides().stream()
+                .filter(p -> PROCESSOR_SERVICE.equals(p.service()))
+                .flatMap(p -> p.providers().stream())
+                .collect(Collectors.toSet());
+
+        assertTrue(
+                "info.picocli.codegen must provide " + PROCESSOR_SERVICE
+                        + " with " + PROCESSOR_IMPL
+                        + " (needed for --processor-module-path discovery). Actual provides: "
+                        + descriptor.provides(),
+                providers.contains(PROCESSOR_IMPL));
+    }
+
+    private static ModuleDescriptor readCodegenModuleDescriptor()
+            throws IOException, URISyntaxException {
+        URL location = NativeImageConfigGeneratorProcessor.class
+                .getProtectionDomain()
+                .getCodeSource()
+                .getLocation();
+        Path path = Paths.get(location.toURI());
+
+        if (Files.isRegularFile(path)) {
+            Optional<ModuleReference> ref = ModuleFinder.of(path).find(MODULE_NAME);
+            if (ref.isPresent()) {
+                return ref.get().descriptor();
+            }
+            fail("Could not find module " + MODULE_NAME + " in jar " + path);
+        }
+
+        // Exploded multi-release layout used by the Gradle build
+        Path moduleInfo = path.resolve("META-INF/versions/9/module-info.class");
+        if (Files.exists(moduleInfo)) {
+            try (InputStream in = Files.newInputStream(moduleInfo)) {
+                return ModuleDescriptor.read(in);
+            }
+        }
+
+        fail("Could not locate module-info for " + MODULE_NAME + " at " + path);
+        return null; // unreachable
+    }
+}

picocli-codegen/src/main/java9/module-info.java

@@ -39,4 +39,10 @@
     exports picocli.codegen.aot.graalvm;
     exports picocli.codegen.aot.graalvm.processor;
     exports picocli.codegen.docgen.manpage;
+
+    // Required for discovery when picocli-codegen is on the processor module path
+    // (--processor-module-path). META-INF/services covers the classpath case.
+    // See https://github.com/remkop/picocli/issues/2464
+    provides javax.annotation.processing.Processor
+            with picocli.codegen.aot.graalvm.processor.NativeImageConfigGeneratorProcessor;
 }