Scala language support

.claude/settings.local.json

@@ -27,7 +27,18 @@
       "mcp__idea__open_file_in_editor",
       "mcp__idea__replace_selected_text",
       "mcp__idea__replace_specific_text",
-      "mcp__idea__search_in_files_content"
+      "mcp__idea__search_in_files_content",
+      "Bash(cat:*)",
+      "Bash(mkdir:*)",
+      "Bash(javac:*)",
+      "Bash(java:*)",
+      "Bash(scalac:*)",
+      "Bash(scala:*)",
+      "Bash(ls:*)",
+      "Bash(../gradlew test:*)",
+      "Bash(./gradlew :rewrite-scala:test --tests \"org.openrewrite.scala.tree.MethodInvocationTest.methodCallOnFieldAccess\" -i)",
+      "Bash(touch:*)",
+      "Bash(sed:*)"
     ],
     "deny": []
   }

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "rewrite-docs"]
+	path = rewrite-docs
+	url = https://github.com/openrewrite/rewrite-docs.git

CLAUDE.md

@@ -2,6 +2,11 @@
 
 This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
 
+## Active Development Plans
+
+- **Scala Language Support**: See [Scala.md](./Scala.md) for the implementation plan and progress tracking.
+- **Language Support Documentation**: As we implement Scala support, we're documenting the process in [Contributing Additional Language Support](./rewrite-docs/docs/authoring-recipes/contributing-language-support.md). This guide should be continuously updated with lessons learned during implementation.
+
 ## Project Overview
 
 OpenRewrite is an automated refactoring ecosystem for source code that eliminates technical debt through AST-based transformations. The project uses a visitor pattern architecture where **Recipes** define transformations and **TreeVisitors** traverse and modify Abstract Syntax Trees (ASTs).

TestComplexType.java

@@ -0,0 +1,21 @@
+import org.openrewrite.java.tree.*;
+import org.openrewrite.marker.Markers;
+import java.util.Collections;
+
+public class TestComplexType {
+    public static void main(String[] args) {
+        // Create a simple identifier "Int"
+        J.Identifier intId = new J.Identifier(
+            Tree.randomId(),
+            Space.EMPTY,
+            Markers.EMPTY,
+            Collections.emptyList(),
+            "Int",
+            null,
+            null
+        );
+
+        System.out.println("Identifier simpleName: " + intId.getSimpleName());
+        System.out.println("Identifier toString: " + intId);
+    }
+}

rewrite-java/src/main/java/org/openrewrite/java/tree/Comment.java

@@ -21,7 +21,7 @@
 import org.openrewrite.marker.Markers;
 
 @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, property = "@c")
-public interface Comment {
+    public interface Comment {
     Markers getMarkers();
     <C extends Comment> C withMarkers(Markers markers);
 

rewrite-scala/TestAssignment.scala

@@ -0,0 +1,33 @@
+import dotty.tools.dotc.ast.Trees.*
+import dotty.tools.dotc.ast.untpd
+import dotty.tools.dotc.core.Contexts.*
+import dotty.tools.dotc.Driver
+import dotty.tools.dotc.util.SourceFile
+import dotty.tools.dotc.parsing.Parsers
+
+@main def testAssignment(): Unit = {
+  val driver = new Driver
+  given Context = driver.getInitialContext
+
+  // Test simple assignment
+  val source1 = SourceFile.virtual("test.scala", "obj.field = 42")
+  val parser1 = new Parsers.Parser(source1)
+  val tree1 = parser1.parse()
+
+  println(s"Assignment AST: ${tree1.getClass.getSimpleName}")
+  tree1 match {
+    case pkg: untpd.PackageDef =>
+      pkg.stats.foreach { stat =>
+        println(s"  Statement: ${stat.getClass.getSimpleName}")
+        stat match {
+          case app: untpd.Apply =>
+            println(s"    Fun: ${app.fun}")
+            println(s"    Args: ${app.args}")
+          case _ =>
+            println(s"    Details: $stat")
+        }
+      }
+    case _ =>
+      println(s"Unexpected: $tree1")
+  }
+}

rewrite-scala/build.gradle.kts

@@ -0,0 +1,54 @@
+plugins {
+    id("org.openrewrite.build.language-library")
+    scala
+}
+
+dependencies {
+    api(project(":rewrite-java"))
+
+    // Scala 3 compiler (dotty) and library
+    implementation("org.scala-lang:scala3-compiler_3:latest.release")
+    implementation("org.scala-lang:scala3-library_3:latest.release")
+
+    compileOnly(project(":rewrite-test"))
+    compileOnly("org.slf4j:slf4j-api:1.7.+")
+
+    api("io.micrometer:micrometer-core:1.9.+")
+
+    api("org.jetbrains:annotations:latest.release")
+
+    api("com.fasterxml.jackson.core:jackson-annotations")
+
+    testImplementation(project(":rewrite-test"))
+    testImplementation(project(":rewrite-java-test"))
+    testImplementation("org.assertj:assertj-core:latest.release")
+    testImplementation("org.junit.jupiter:junit-jupiter-api:latest.release")
+    testImplementation("org.junit.jupiter:junit-jupiter-params:latest.release")
+    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:latest.release")
+}
+
+// Configure Scala source sets and compilation order
+sourceSets {
+    main {
+        scala {
+            srcDirs("src/main/scala")
+        }
+    }
+}
+
+// Configure mixed Java/Scala compilation
+// Scala needs to see Java classes from the same module
+tasks.named<ScalaCompile>("compileScala") {
+    // Include Java source files in Scala compilation
+    source(sourceSets.main.get().java)
+    // Scala compiler will compile both Java and Scala files together
+    classpath = sourceSets.main.get().compileClasspath
+}
+
+// Ensure Java compilation uses output from Scala compilation
+// Since Scala already compiled Java files, we just need to ensure the classpath is correct
+tasks.named<JavaCompile>("compileJava") {
+    dependsOn("compileScala")
+    // Exclude Java files from Java compilation since Scala already compiled them
+    exclude("**/*.java")
+}

rewrite-scala/src/main/java/org/openrewrite/scala/Assertions.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2025 the original author or authors.
+ * <p>
+ * Licensed 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.scala;
+
+import org.intellij.lang.annotations.Language;
+import org.jspecify.annotations.Nullable;
+import org.openrewrite.SourceFile;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.scala.tree.S;
+import org.openrewrite.test.SourceSpec;
+import org.openrewrite.test.SourceSpecs;
+
+import java.util.function.Consumer;
+
+import static org.openrewrite.java.Assertions.sourceSet;
+import static org.openrewrite.test.SourceSpecs.dir;
+
+public class Assertions {
+
+    private Assertions() {
+    }
+
+    private static ScalaParser.Builder scalaParser = ScalaParser.builder()
+            .classpath(JavaParser.runtimeClasspath())
+            .logCompilationWarningsAndErrors(true);
+
+    public static SourceSpecs scala(@Language("scala") @Nullable String before) {
+        return scala(before, s -> {
+        });
+    }
+
+    public static SourceSpecs scala(@Language("scala") @Nullable String before, Consumer<SourceSpec<S.CompilationUnit>> spec) {
+        SourceSpec<S.CompilationUnit> scala = new SourceSpec<>(S.CompilationUnit.class, null, scalaParser, before, null);
+        spec.accept(scala);
+        return scala;
+    }
+
+    public static SourceSpecs scala(@Language("scala") @Nullable String before, @Language("scala") @Nullable String after) {
+        return scala(before, after, s -> {
+        });
+    }
+
+    public static SourceSpecs scala(@Language("scala") @Nullable String before, @Language("scala") @Nullable String after,
+                                    Consumer<SourceSpec<S.CompilationUnit>> spec) {
+        SourceSpec<S.CompilationUnit> scala = new SourceSpec<>(S.CompilationUnit.class, null, scalaParser, before, s -> after);
+        spec.accept(scala);
+        return scala;
+    }
+
+    public static SourceSpecs srcMainScala(Consumer<SourceSpec<SourceFile>> spec, SourceSpecs... scalaSources) {
+        return dir("src/main/scala", spec, scalaSources);
+    }
+
+    public static SourceSpecs srcMainScala(SourceSpecs... scalaSources) {
+        return srcMainScala(spec -> sourceSet(spec, "main"), scalaSources);
+    }
+
+    public static SourceSpecs srcTestScala(Consumer<SourceSpec<SourceFile>> spec, SourceSpecs... scalaSources) {
+        return dir("src/test/scala", spec, scalaSources);
+    }
+
+    public static SourceSpecs srcTestScala(SourceSpecs... scalaSources) {
+        return srcTestScala(spec -> sourceSet(spec, "test"), scalaSources);
+    }
+}