[gazelle] Detect fully qualified class names in kotlin code

java/gazelle/testdata/kt_fqn_deps/BUILD.in

@@ -0,0 +1 @@
+# gazelle:jvm_kotlin_enabled true

java/gazelle/testdata/kt_fqn_deps/BUILD.out

@@ -0,0 +1 @@
+# gazelle:jvm_kotlin_enabled true

java/gazelle/testdata/kt_fqn_deps/README.md

@@ -0,0 +1,13 @@
+# Kotlin fully qualified name dependencies
+
+Test that Gazelle detects dependencies from fully qualified class references
+used directly in Kotlin expressions, without corresponding import statements.
+
+When Kotlin code uses FQN constructor calls like
+`com.example.errors.CustomError(e)` instead of importing `CustomError`, the
+parser must still recognize the cross-package dependency. This is common when
+there are name conflicts (e.g., a custom `InterruptedException` alongside
+`java.util.concurrent.InterruptedException`).
+
+The `app/src` package uses a FQN constructor call to `com.example.errors.CustomError`
+and should get a `deps` entry for `//errors/src`.

java/gazelle/testdata/kt_fqn_deps/WORKSPACE

@@ -0,0 +1,19 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+rules_kotlin_version = "1.9.6"
+
+rules_kotlin_sha = "3b772976fec7bdcda1d84b9d39b176589424c047eb2175bed09aac630e50af43"
+
+http_archive(
+    name = "rules_kotlin",
+    sha256 = rules_kotlin_sha,
+    urls = ["https://github.com/bazelbuild/rules_kotlin/releases/download/v%s/rules_kotlin-v%s.tar.gz" % (rules_kotlin_version, rules_kotlin_version)],
+)
+
+load("@rules_kotlin//kotlin:repositories.bzl", "kotlin_repositories")
+
+kotlin_repositories()
+
+load("@rules_kotlin//kotlin:core.bzl", "kt_register_toolchains")
+
+kt_register_toolchains()

java/gazelle/testdata/kt_fqn_deps/app/src/App.kt

@@ -0,0 +1,9 @@
+package com.example.app
+
+fun doWork() {
+    try {
+        // work
+    } catch (e: Exception) {
+        throw com.example.errors.CustomError(e)
+    }
+}

java/gazelle/testdata/kt_fqn_deps/app/src/BUILD.out

@@ -0,0 +1,8 @@
+load("@rules_kotlin//kotlin:jvm.bzl", "kt_jvm_library")
+
+kt_jvm_library(
+    name = "src",
+    srcs = ["App.kt"],
+    visibility = ["//:__subpackages__"],
+    deps = ["//errors/src"],
+)

java/gazelle/testdata/kt_fqn_deps/errors/src/BUILD.out

@@ -0,0 +1,7 @@
+load("@rules_kotlin//kotlin:jvm.bzl", "kt_jvm_library")
+
+kt_jvm_library(
+    name = "src",
+    srcs = ["CustomError.kt"],
+    visibility = ["//:__subpackages__"],
+)

java/gazelle/testdata/kt_fqn_deps/errors/src/CustomError.kt

@@ -0,0 +1,3 @@
+package com.example.errors
+
+class CustomError(cause: Exception) : RuntimeException(cause)

java/gazelle/testdata/kt_fqn_deps/maven_install.json

@@ -0,0 +1 @@
+{"version": "2"}

java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/KtParser.java

@@ -605,6 +605,29 @@ public void visitDotQualifiedExpression(KtDotQualifiedExpression expression) {
           String functionName = callExpr.getCalleeExpression().getText();
 
           checkExtensionFunctionCall(receiverType, functionName);
+
+          // Detect FQN constructor call: com.example.ClassName(args)
+          // Mirrors ClasspathParser.visitNewClass → checkFullyQualifiedType
+          if (isLikelyClassName(functionName) && receiverType.contains(".")) {
+            String fqClassName = receiverType + "." + functionName;
+            packageData.usedTypes.add(fqClassName);
+          }
+        }
+      }
+
+      // Detect FQN class reference: com.example.ClassName (as selector of a DQE)
+      // Mirrors ClasspathParser.visitMethodInvocation + looksLikeClassName
+      if (selectorExpression instanceof KtSimpleNameExpression) {
+        String selectorName = ((KtSimpleNameExpression) selectorExpression).getReferencedName();
+        if (isLikelyClassName(selectorName)) {
+          KtExpression receiverExpr = expression.getReceiverExpression();
+          if (receiverExpr != null) {
+            String receiverText = receiverExpr.getText();
+            if (receiverText.contains(".")) {
+              String fqClassName = receiverText + "." + selectorName;
+              packageData.usedTypes.add(fqClassName);
+            }
+          }
         }
       }
 

java/test/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/KtParserTest.java

@@ -148,22 +148,25 @@ public void constantTest() throws IOException {
         data.perClassData.keySet());
   }
 
-  // @Test
-  // public void fullyQualifiedClassAndFunctionUse() throws IOException {
-  //   ParsedPackageData data = parser.parseClasses(getPathsWithNames("FullyQualifieds.kt"));
-  //   assertEquals(
-  //     Set.of("com.example"),
-  //     data.usedPackagesWithoutSpecificTypes);
-  //   assertEquals(
-  //       Set.of(
-  //           "workspace.com.gazelle.java.javaparser.generators.DeleteBookRequest",
-  //           "workspace.com.gazelle.java.javaparser.generators.DeleteBookResponse",
-  //           "workspace.com.gazelle.java.javaparser.utils.Printer",
-  //           "workspace.com.gazelle.java.javaparser.factories.Factory",
-  //           "java.util.ArrayList",
-  //           "com.example.PrivateArg"),
-  //       data.usedTypes);
-  // }
+  @Test
+  public void detectsFqnClassReferences() throws IOException {
+    ParsedPackageData data = parser.parseClasses(getPathsWithNames("FullyQualifieds.kt"));
+
+    // FQN constructor calls and class references detected via visitDotQualifiedExpression
+    assertTrue(
+        data.usedTypes.contains(
+            "workspace.com.gazelle.java.javaparser.generators.DeleteBookRequest"),
+        "Should detect FQN constructor call: " + data.usedTypes);
+    assertTrue(
+        data.usedTypes.contains("workspace.com.gazelle.java.javaparser.utils.Printer"),
+        "Should detect FQN class reference (static method call): " + data.usedTypes);
+    assertTrue(
+        data.usedTypes.contains("workspace.com.gazelle.java.javaparser.factories.Factory"),
+        "Should detect FQN class reference (factory call): " + data.usedTypes);
+    assertTrue(
+        data.usedTypes.contains("java.util.ArrayList"),
+        "Should detect FQN generic constructor call: " + data.usedTypes);
+  }
 
   @Test
   public void staticImportsTest() throws IOException {