feat: Support providing compiler arguments

model/src/main/java/com/microsoft/java/bs/gradle/model/GradleSourceSet.java

@@ -1,6 +1,7 @@
 package com.microsoft.java.bs.gradle.model;
 
 import java.io.File;
+import java.util.List;
 import java.util.Set;
 
 /**
@@ -89,6 +90,11 @@ public interface GradleSourceSet {
    */
   public String getTargetCompatibility();
 
+  /**
+   * The list of compiler arguments.
+   */
+  public List<String> getCompilerArgs();
+
   /**
    * Module dependencies.
    */

plugin/src/main/java/com/microsoft/java/bs/gradle/plugin/SourceSetsModelBuilder.java

@@ -7,6 +7,7 @@
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -102,6 +103,7 @@ public Object buildAll(String modelName, Project rootProject) {
         gradleSourceSet.setGradleVersion(gradleVersion);
         gradleSourceSet.setSourceCompatibility(getSourceCompatibility(project, sourceSet));
         gradleSourceSet.setTargetCompatibility(getTargetCompatibility(project, sourceSet));
+        gradleSourceSet.setCompilerArgs(getCompilerArgs(project, sourceSet));
         gradleSourceSets.add(gradleSourceSet);
       });
 
@@ -302,6 +304,18 @@ private String getTargetCompatibility(Project project, SourceSet sourceSet) {
     return "";
   }
 
+  /**
+   * Get the compilation arguments of the source set.
+   */
+  private List<String> getCompilerArgs(Project project, SourceSet sourceSet) {
+    JavaCompile javaCompile = getJavaCompileTask(project, sourceSet);
+    if (javaCompile != null) {
+      return javaCompile.getOptions().getCompilerArgs();
+    }
+
+    return Collections.emptyList();
+  }
+
   private Set<String> getClasspathConfigurationNames(SourceSet sourceSet) {
     Set<String> configurationNames = new HashSet<>();
     configurationNames.add(sourceSet.getCompileClasspathConfigurationName());

plugin/src/main/java/com/microsoft/java/bs/gradle/plugin/model/DefaultGradleSourceSet.java

@@ -2,6 +2,7 @@
 
 import java.io.File;
 import java.io.Serializable;
+import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 
@@ -49,6 +50,8 @@ public class DefaultGradleSourceSet implements GradleSourceSet, Serializable {
 
   private String targetCompatibility;
 
+  private List<String> compilerArgs;
+
   private Set<GradleModuleDependency> moduleDependencies;
 
   private Set<GradleProjectDependency> projectDependencies;
@@ -191,6 +194,14 @@ public void setTargetCompatibility(String targetCompatibility) {
     this.targetCompatibility = targetCompatibility;
   }
 
+  public List<String> getCompilerArgs() {
+    return compilerArgs;
+  }
+
+  public void setCompilerArgs(List<String> compilerArgs) {
+    this.compilerArgs = compilerArgs;
+  }
+
   public Set<GradleModuleDependency> getModuleDependencies() {
     return moduleDependencies;
   }
@@ -210,10 +221,11 @@ public void setProjectDependencies(Set<GradleProjectDependency> projectDependenc
   @Override
   public int hashCode() {
     return Objects.hash(projectName, projectPath, projectDir,
-        rootDir, sourceSetName, classesTaskName, sourceDirs, generatedSourceDirs,
-        sourceOutputDir, resourceDirs, resourceOutputDir,
-        javaHome, javaVersion, gradleVersion, sourceCompatibility,
-        targetCompatibility, moduleDependencies, projectDependencies);
+        rootDir, sourceSetName, classesTaskName, sourceDirs,
+        generatedSourceDirs, sourceOutputDir, resourceDirs,
+        resourceOutputDir, javaHome, javaVersion, gradleVersion,
+        sourceCompatibility, targetCompatibility, compilerArgs,
+        moduleDependencies, projectDependencies);
   }
 
   @Override
@@ -244,6 +256,7 @@ public boolean equals(Object obj) {
         && Objects.equals(gradleVersion, other.gradleVersion)
         && Objects.equals(sourceCompatibility, other.sourceCompatibility)
         && Objects.equals(targetCompatibility, other.targetCompatibility)
+        && Objects.equals(compilerArgs, other.compilerArgs)
         && Objects.equals(moduleDependencies, other.moduleDependencies)
         && Objects.equals(projectDependencies, other.projectDependencies);
   }

plugin/src/test/java/com/microsoft/java/bs/gradle/plugin/GradleBuildServerPluginTest.java

@@ -63,6 +63,7 @@ void testModelBuilder() throws IOException {
         assertNotNull(gradleSourceSet.getJavaVersion());
         assertNotNull(gradleSourceSet.getSourceCompatibility());
         assertNotNull(gradleSourceSet.getTargetCompatibility());
+        assertNotNull(gradleSourceSet.getCompilerArgs());
         assertNotNull(gradleSourceSet.getGradleVersion());
         assertNotNull(gradleSourceSet.getModuleDependencies());
         assertTrue(gradleSourceSet.getModuleDependencies().stream().anyMatch(

server/src/main/java/com/microsoft/java/bs/core/internal/server/GradleBuildServer.java

@@ -35,6 +35,9 @@
 import ch.epfl.scala.bsp4j.InitializeBuildResult;
 import ch.epfl.scala.bsp4j.InverseSourcesParams;
 import ch.epfl.scala.bsp4j.InverseSourcesResult;
+import ch.epfl.scala.bsp4j.JavaBuildServer;
+import ch.epfl.scala.bsp4j.JavacOptionsParams;
+import ch.epfl.scala.bsp4j.JavacOptionsResult;
 import ch.epfl.scala.bsp4j.OutputPathsParams;
 import ch.epfl.scala.bsp4j.OutputPathsResult;
 import ch.epfl.scala.bsp4j.ResourcesParams;
@@ -50,7 +53,7 @@
 /**
  * The implementation of the Build Server Protocol.
  */
-public class GradleBuildServer implements BuildServer {
+public class GradleBuildServer implements BuildServer, JavaBuildServer {
 
   private LifecycleService lifecycleService;
 
@@ -163,6 +166,12 @@ public CompletableFuture<DependencyModulesResult> buildTargetDependencyModules(
         buildTargetService.getBuildTargetDependencyModules(params));
   }
 
+  @Override
+  public CompletableFuture<JavacOptionsResult> buildTargetJavacOptions(JavacOptionsParams params) {
+    return handleRequest("buildTarget/javacOptions", cc ->
+        buildTargetService.getBuildTargetrJavacOptions(params));
+  }
+
   private void handleNotification(String methodName, Runnable runnable, boolean async) {
     LogEntity entity = new LogEntity.Builder()
         .operationName(escapeMethodName(methodName))

server/src/main/java/com/microsoft/java/bs/core/internal/services/BuildTargetService.java

@@ -5,6 +5,7 @@
 import java.io.File;
 import java.net.URI;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -30,6 +31,9 @@
 import ch.epfl.scala.bsp4j.DependencyModulesItem;
 import ch.epfl.scala.bsp4j.DependencyModulesParams;
 import ch.epfl.scala.bsp4j.DependencyModulesResult;
+import ch.epfl.scala.bsp4j.JavacOptionsItem;
+import ch.epfl.scala.bsp4j.JavacOptionsParams;
+import ch.epfl.scala.bsp4j.JavacOptionsResult;
 import ch.epfl.scala.bsp4j.MavenDependencyModule;
 import ch.epfl.scala.bsp4j.MavenDependencyModuleArtifact;
 import ch.epfl.scala.bsp4j.OutputPathItem;
@@ -234,6 +238,30 @@ public CompileResult compile(CompileParams params) {
     return result;
   }
 
+  /**
+   * Get the compiler options.
+   */
+  public JavacOptionsResult getBuildTargetrJavacOptions(JavacOptionsParams params) {
+    List<JavacOptionsItem> items = new ArrayList<>();
+    for (BuildTargetIdentifier btId : params.getTargets()) {
+      GradleBuildTarget target = buildTargetManager.getGradleBuildTarget(btId);
+      if (target == null) {
+        LOGGER.warning("Skip javac options collection for the build target: " + btId.getUri()
+            + ". Because it cannot be found in the cache.");
+        continue;
+      }
+
+      GradleSourceSet sourceSet = target.getSourceSet();
+      items.add(new JavacOptionsItem(
+          btId,
+          sourceSet.getCompilerArgs(),
+          Collections.emptyList(), // classpath, not support currently 
+          "" // classDirectory, not support currently
+      ));
+    }
+    return new JavacOptionsResult(items);
+  }
+
   /**
    * Group the build targets by the project root directory,
    * projects with the same root directory can run their tasks

server/src/test/java/com/microsoft/java/bs/core/internal/services/BuildTargetServiceTest.java

@@ -8,6 +8,7 @@
 
 import java.io.File;
 import java.net.URI;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
@@ -29,6 +30,8 @@
 import ch.epfl.scala.bsp4j.DependencyModule;
 import ch.epfl.scala.bsp4j.DependencyModulesParams;
 import ch.epfl.scala.bsp4j.DependencyModulesResult;
+import ch.epfl.scala.bsp4j.JavacOptionsParams;
+import ch.epfl.scala.bsp4j.JavacOptionsResult;
 import ch.epfl.scala.bsp4j.MavenDependencyModule;
 import ch.epfl.scala.bsp4j.MavenDependencyModuleArtifact;
 import ch.epfl.scala.bsp4j.OutputPathsParams;
@@ -212,4 +215,27 @@ public String getClassifier() {
     MavenDependencyModuleArtifact artifact = module.getArtifacts().get(0);
     assertEquals("sources", artifact.getClassifier());
   }
+
+  @Test
+  void testGetJavacOptions() {
+    GradleBuildTarget gradleBuildTarget = mock(GradleBuildTarget.class);
+    when(buildTargetManager.getGradleBuildTarget(any())).thenReturn(gradleBuildTarget);
+
+    GradleSourceSet gradleSourceSet = mock(GradleSourceSet.class);
+    when(gradleBuildTarget.getSourceSet()).thenReturn(gradleSourceSet);
+
+    List<String> compilerArgs = new ArrayList<>();
+
+    compilerArgs.add("--add-opens");
+    compilerArgs.add("java.base/java.lang=ALL-UNNAMED");
+    when(gradleSourceSet.getCompilerArgs()).thenReturn(compilerArgs);
+
+    BuildTargetService buildTargetService = new BuildTargetService(buildTargetManager,
+        preferenceManager);
+    JavacOptionsResult javacOptions = buildTargetService.getBuildTargetrJavacOptions(
+        new JavacOptionsParams(Arrays.asList(new BuildTargetIdentifier("test"))));
+
+    assertEquals(1, javacOptions.getItems().size());
+    assertEquals(2, javacOptions.getItems().get(0).getOptions().size());
+  }
 }