[MNG-8615] [MNG-8616] Maven core extensions handling improvements

api/maven-api-cli/pom.xml

@@ -59,6 +59,8 @@
             <template>model.vm</template>
           </templates>
           <params>
+            <param>locationTracking=true</param>
+            <param>generateLocationClasses=true</param>
             <param>packageModelV4=org.apache.maven.api.cli.extensions</param>
             <param>packageToolV4=org.apache.maven.cli.internal.extension.io</param>
           </params>

api/maven-api-cli/src/main/java/org/apache/maven/api/cli/CoreExtensions.java

@@ -0,0 +1,48 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.api.cli;
+
+import java.nio.file.Path;
+import java.util.List;
+
+import org.apache.maven.api.Constants;
+import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.cli.extensions.CoreExtension;
+
+import static java.util.Objects.requireNonNull;
+
+/**
+ * Represents the list of core extensions configured at one source. The list is validated (are GA unique), but no
+ * other logic than that is applied.
+ *
+ * @since 4.0.0
+ * @param source The source file of core extensions, is never {@code null}.
+ * @param coreExtensions The configured core extensions, is never {@code null}. Contents of list is guaranteed to be unique by GA.
+ *
+ * @see Constants#MAVEN_PROJECT_EXTENSIONS
+ * @see Constants#MAVEN_USER_EXTENSIONS
+ * @see Constants#MAVEN_INSTALLATION_EXTENSIONS
+ */
+@Experimental
+public record CoreExtensions(Path source, List<CoreExtension> coreExtensions) {
+    public CoreExtensions(Path source, List<CoreExtension> coreExtensions) {
+        this.source = requireNonNull(source, "source");
+        this.coreExtensions = requireNonNull(coreExtensions, "coreExtensions");
+    }
+}

api/maven-api-cli/src/main/java/org/apache/maven/api/cli/InvokerRequest.java

@@ -28,7 +28,6 @@
 import org.apache.maven.api.annotations.Experimental;
 import org.apache.maven.api.annotations.Immutable;
 import org.apache.maven.api.annotations.Nonnull;
-import org.apache.maven.api.cli.extensions.CoreExtension;
 import org.apache.maven.api.services.Lookup;
 import org.apache.maven.api.services.MessageBuilderFactory;
 
@@ -172,12 +171,16 @@ default Optional<OutputStream> stdErr() {
     }
 
     /**
-     * Returns a list of core extensions, if configured in the .mvn/extensions.xml file.
+     * Returns a list of core extensions from all sources, that were discovered and loaded. Each instance of
+     * {@link CoreExtensions} is validated, but the list elements may have overlapping elements, that requires
+     * some logic to sort out (like precedence).
+     * <p>
+     * The list of {@link CoreExtensions} if present, is in precedence order.
      *
-     * @return an {@link Optional} containing the list of core extensions, or empty if not configured
+     * @return an {@link Optional} containing the {@link CoreExtensions}, or empty if not configured
      */
     @Nonnull
-    Optional<List<CoreExtension>> coreExtensions();
+    Optional<List<CoreExtensions>> coreExtensions();
 
     /**
      * Returns the options associated with this invocation request.

api/maven-api-cli/src/main/java/org/apache/maven/api/cli/ParserRequest.java

@@ -317,7 +317,7 @@ public ParserRequest build() {
                     command,
                     commandName,
                     List.copyOf(args),
-                    logger,
+                    lookup.lookupOptional(Logger.class).orElse(logger),
                     messageBuilderFactory,
                     lookup,
                     cwd,

api/maven-api-cli/src/main/java/org/apache/maven/api/cli/extensions/package-info.java

@@ -19,8 +19,6 @@
 
 /**
  * Provides support for Maven core extensions configuration and management.
- * Core extensions can be configured through {@code .mvn/extensions.xml} in the project
- * base directory to enhance Maven's capabilities during build execution.
  *
  * <p>This package contains classes for:</p>
  * <ul>

compat/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java

@@ -60,6 +60,7 @@
 import org.apache.maven.Maven;
 import org.apache.maven.api.Constants;
 import org.apache.maven.api.cli.extensions.CoreExtension;
+import org.apache.maven.api.cli.extensions.InputSource;
 import org.apache.maven.api.services.MessageBuilder;
 import org.apache.maven.api.services.MessageBuilderFactory;
 import org.apache.maven.building.FileSource;
@@ -858,7 +859,9 @@ private List<CoreExtension> readCoreExtensionsDescriptor(String extensionsFile)
             Path extensionsPath = Path.of(extensionsFile);
             if (Files.exists(extensionsPath)) {
                 try (InputStream is = Files.newInputStream(extensionsPath)) {
-                    return new CoreExtensionsStaxReader().read(is, true).getExtensions();
+                    return new CoreExtensionsStaxReader()
+                            .read(is, true, new InputSource(extensionsFile))
+                            .getExtensions();
                 }
             }
         }

impl/maven-cli/pom.xml

@@ -261,6 +261,7 @@ under the License.
           <params>
             <param>packageModelV4=org.apache.maven.api.cli.extensions</param>
             <param>packageToolV4=org.apache.maven.cling.internal.extension.io</param>
+            <param>locationTracking=true</param>
           </params>
           <velocityBasedir>${project.basedir}/../../src/mdo</velocityBasedir>
         </configuration>

impl/maven-cli/src/main/java/org/apache/maven/cling/extensions/BootstrapCoreExtensionManager.java

@@ -132,7 +132,7 @@ public BootstrapCoreExtensionManager(
         this.interpolator = interpolator;
     }
 
-    public List<CoreExtensionEntry> loadCoreExtensions(
+    public List<LoadedCoreExtension> loadCoreExtensions(
             MavenExecutionRequest request, Set<String> providedArtifacts, List<CoreExtension> extensions)
             throws Exception {
         try (CloseableSession repoSession = repositorySystemSessionFactory
@@ -150,22 +150,22 @@ public List<CoreExtensionEntry> loadCoreExtensions(
         }
     }
 
-    private List<CoreExtensionEntry> resolveCoreExtensions(
+    private List<LoadedCoreExtension> resolveCoreExtensions(
             RepositorySystemSession repoSession,
             List<RemoteRepository> repositories,
             Set<String> providedArtifacts,
             List<CoreExtension> configuration,
             UnaryOperator<String> interpolator)
             throws Exception {
-        List<CoreExtensionEntry> extensions = new ArrayList<>();
+        List<LoadedCoreExtension> extensions = new ArrayList<>();
 
         DependencyFilter dependencyFilter = new ExclusionsDependencyFilter(providedArtifacts);
 
         for (CoreExtension extension : configuration) {
             List<Artifact> artifacts =
                     resolveExtension(extension, repoSession, repositories, dependencyFilter, interpolator);
             if (!artifacts.isEmpty()) {
-                extensions.add(createExtension(extension, artifacts));
+                extensions.add(new LoadedCoreExtension(extension, createExtension(extension, artifacts)));
             }
         }
 

impl/maven-cli/src/main/java/org/apache/maven/cling/extensions/LoadedCoreExtension.java

@@ -0,0 +1,29 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.cling.extensions;
+
+import org.apache.maven.api.cli.extensions.CoreExtension;
+import org.apache.maven.extension.internal.CoreExtensionEntry;
+
+/**
+ * Represents a core extension that has been selected to be loaded.
+ * @param coreExtension The extension configuration entry with location tracking.
+ * @param entry The loaded entry with descriptor.
+ */
+public record LoadedCoreExtension(CoreExtension coreExtension, CoreExtensionEntry entry) {}

impl/maven-cli/src/main/java/org/apache/maven/cling/invoker/BaseInvokerRequest.java

@@ -25,9 +25,9 @@
 
 import org.apache.maven.api.annotations.Nonnull;
 import org.apache.maven.api.annotations.Nullable;
+import org.apache.maven.api.cli.CoreExtensions;
 import org.apache.maven.api.cli.InvokerRequest;
 import org.apache.maven.api.cli.ParserRequest;
-import org.apache.maven.api.cli.extensions.CoreExtension;
 
 import static java.util.Objects.requireNonNull;
 
@@ -41,7 +41,7 @@ public abstract class BaseInvokerRequest implements InvokerRequest {
     private final Map<String, String> systemProperties;
     private final Path topDirectory;
     private final Path rootDirectory;
-    private final List<CoreExtension> coreExtensions;
+    private final List<CoreExtensions> coreExtensions;
 
     @SuppressWarnings("ParameterNumber")
     public BaseInvokerRequest(
@@ -54,7 +54,7 @@ public BaseInvokerRequest(
             @Nonnull Map<String, String> systemProperties,
             @Nonnull Path topDirectory,
             @Nullable Path rootDirectory,
-            @Nullable List<CoreExtension> coreExtensions) {
+            @Nullable List<CoreExtensions> coreExtensions) {
         this.parserRequest = requireNonNull(parserRequest);
         this.parsingFailed = parsingFailed;
         this.cwd = requireNonNull(cwd);
@@ -114,7 +114,7 @@ public Optional<Path> rootDirectory() {
     }
 
     @Override
-    public Optional<List<CoreExtension>> coreExtensions() {
+    public Optional<List<CoreExtensions>> coreExtensions() {
         return Optional.ofNullable(coreExtensions);
     }
 }

impl/maven-cli/src/main/java/org/apache/maven/cling/invoker/BaseParser.java

@@ -34,14 +34,18 @@
 import java.util.Objects;
 import java.util.Properties;
 import java.util.function.UnaryOperator;
+import java.util.stream.Collectors;
 
 import org.apache.maven.api.Constants;
 import org.apache.maven.api.annotations.Nullable;
+import org.apache.maven.api.cli.CoreExtensions;
 import org.apache.maven.api.cli.InvokerRequest;
 import org.apache.maven.api.cli.Options;
 import org.apache.maven.api.cli.Parser;
 import org.apache.maven.api.cli.ParserRequest;
 import org.apache.maven.api.cli.extensions.CoreExtension;
+import org.apache.maven.api.cli.extensions.InputLocation;
+import org.apache.maven.api.cli.extensions.InputSource;
 import org.apache.maven.api.services.Interpolator;
 import org.apache.maven.cling.internal.extension.io.CoreExtensionsStaxReader;
 import org.apache.maven.cling.props.MavenPropertiesLoader;
@@ -79,7 +83,9 @@ public LocalContext(ParserRequest parserRequest) {
         @Nullable
         public Path rootDirectory;
 
-        public List<CoreExtension> extensions;
+        @Nullable
+        public List<CoreExtensions> extensions;
+
         public Options options;
 
         public Map<String, String> extraInterpolationSource() {
@@ -425,59 +431,73 @@ protected Map<String, String> populateUserProperties(LocalContext context) {
 
     protected abstract Options assembleOptions(List<Options> parsedOptions);
 
-    protected List<CoreExtension> readCoreExtensionsDescriptor(LocalContext context) {
-        String installationExtensionsFile = context.userProperties.get(Constants.MAVEN_INSTALLATION_EXTENSIONS);
-        ArrayList<CoreExtension> installationExtensions = new ArrayList<>(readCoreExtensionsDescriptorFromFile(
-                context.installationDirectory.resolve(installationExtensionsFile)));
-
-        String userExtensionsFile = context.userProperties.get(Constants.MAVEN_USER_EXTENSIONS);
-        ArrayList<CoreExtension> userExtensions = new ArrayList<>(
-                readCoreExtensionsDescriptorFromFile(context.userHomeDirectory.resolve(userExtensionsFile)));
-
-        String projectExtensionsFile = context.userProperties.get(Constants.MAVEN_PROJECT_EXTENSIONS);
-        ArrayList<CoreExtension> projectExtensions =
-                new ArrayList<>(readCoreExtensionsDescriptorFromFile(context.cwd.resolve(projectExtensionsFile)));
-
-        // merge these 3 but check for GA uniqueness; we don't want to load up same extension w/ different Vs
-        HashMap<String, String> gas = new HashMap<>();
-        ArrayList<String> conflicts = new ArrayList<>();
-
-        ArrayList<CoreExtension> coreExtensions =
-                new ArrayList<>(installationExtensions.size() + userExtensions.size() + projectExtensions.size());
-        coreExtensions.addAll(mergeExtensions(installationExtensions, installationExtensionsFile, gas, conflicts));
-        coreExtensions.addAll(mergeExtensions(userExtensions, userExtensionsFile, gas, conflicts));
-        coreExtensions.addAll(mergeExtensions(projectExtensions, projectExtensionsFile, gas, conflicts));
-
-        if (!conflicts.isEmpty()) {
-            throw new IllegalStateException("Extension conflicts: " + String.join("; ", conflicts));
+    /**
+     * Important: This method must return list of {@link CoreExtensions} in precedence order.
+     */
+    protected List<CoreExtensions> readCoreExtensionsDescriptor(LocalContext context) {
+        ArrayList<CoreExtensions> result = new ArrayList<>();
+        Path file;
+        List<CoreExtension> loaded;
+
+        // project
+        file = context.cwd.resolve(context.userProperties.get(Constants.MAVEN_PROJECT_EXTENSIONS));
+        loaded = readCoreExtensionsDescriptorFromFile(file);
+        if (!loaded.isEmpty()) {
+            result.add(new CoreExtensions(file, loaded));
         }
 
-        return coreExtensions;
-    }
+        // user
+        file = context.userHomeDirectory.resolve(context.userProperties.get(Constants.MAVEN_USER_EXTENSIONS));
+        loaded = readCoreExtensionsDescriptorFromFile(file);
+        if (!loaded.isEmpty()) {
+            result.add(new CoreExtensions(file, loaded));
+        }
 
-    private List<CoreExtension> mergeExtensions(
-            List<CoreExtension> extensions, String extensionsSource, Map<String, String> gas, List<String> conflicts) {
-        for (CoreExtension extension : extensions) {
-            String ga = extension.getGroupId() + ":" + extension.getArtifactId();
-            if (gas.containsKey(ga)) {
-                conflicts.add(ga + " from " + extensionsSource + " already specified in " + gas.get(ga));
-            } else {
-                gas.put(ga, extensionsSource);
-            }
+        // installation
+        file = context.installationDirectory.resolve(
+                context.userProperties.get(Constants.MAVEN_INSTALLATION_EXTENSIONS));
+        loaded = readCoreExtensionsDescriptorFromFile(file);
+        if (!loaded.isEmpty()) {
+            result.add(new CoreExtensions(file, loaded));
         }
-        return extensions;
+
+        return result.isEmpty() ? null : List.copyOf(result);
     }
 
     protected List<CoreExtension> readCoreExtensionsDescriptorFromFile(Path extensionsFile) {
         try {
             if (extensionsFile != null && Files.exists(extensionsFile)) {
                 try (InputStream is = Files.newInputStream(extensionsFile)) {
-                    return new CoreExtensionsStaxReader().read(is, true).getExtensions();
+                    return validateCoreExtensionsDescriptorFromFile(
+                            extensionsFile,
+                            List.copyOf(new CoreExtensionsStaxReader()
+                                    .read(is, true, new InputSource(extensionsFile.toString()))
+                                    .getExtensions()));
                 }
             }
             return List.of();
         } catch (XMLStreamException | IOException e) {
             throw new IllegalArgumentException("Failed to parse extensions file: " + extensionsFile, e);
         }
     }
+
+    protected List<CoreExtension> validateCoreExtensionsDescriptorFromFile(
+            Path extensionFile, List<CoreExtension> coreExtensions) {
+        Map<String, List<InputLocation>> gasLocations = new HashMap<>();
+        for (CoreExtension coreExtension : coreExtensions) {
+            String ga = coreExtension.getGroupId() + ":" + coreExtension.getArtifactId();
+            InputLocation location = coreExtension.getLocation("");
+            gasLocations.computeIfAbsent(ga, k -> new ArrayList<>()).add(location);
+        }
+        if (gasLocations.values().stream().noneMatch(l -> l.size() > 1)) {
+            return coreExtensions;
+        }
+        throw new IllegalStateException("Extension conflicts in file " + extensionFile + ": "
+                + gasLocations.entrySet().stream()
+                        .map(e -> e.getKey() + " defined on lines "
+                                + e.getValue().stream()
+                                        .map(l -> String.valueOf(l.getLineNumber()))
+                                        .collect(Collectors.joining(", ")))
+                        .collect(Collectors.joining("; ")));
+    }
 }

impl/maven-cli/src/main/java/org/apache/maven/cling/invoker/ContainerCapsuleFactory.java

@@ -30,5 +30,6 @@ public interface ContainerCapsuleFactory<C extends LookupContext> {
      * Creates container capsule.
      */
     @Nonnull
-    ContainerCapsule createContainerCapsule(LookupInvoker<C> invoker, C context) throws Exception;
+    ContainerCapsule createContainerCapsule(
+            LookupInvoker<C> invoker, C context, CoreExtensionSelector<C> coreExtensionSelector) throws Exception;
 }