From 642be58d44488ca5f1a3eab05e87464f1d003b00 Mon Sep 17 00:00:00 2001
From: calm <148254234+calm329@users.noreply.github.com>
Date: Tue, 20 Jan 2026 23:31:07 -0800
Subject: [PATCH] Add scripted test for #6175 (#8598)

This PR adds a scripted test to prevent regression of issue #6175, where `MethodHandle.invokeExact` failed to compile on JDK 15+ when using `-release 11`.

Changes:
- Added `sbt-app/src/sbt-test/java/method-handle-release/` scripted test
- Test uses Scala 2.13.16 with `-release:11` to reproduce the original issue scenario
- Verifies that polymorphic signature methods compile correctly under cross-version targeting
---
 .../java/method-handle-release/build.sbt      |  2 ++
 .../src/main/scala/Main.scala                 | 19 +++++++++++++++++++
 .../sbt-test/java/method-handle-release/test  |  3 +++
 3 files changed, 24 insertions(+)
 create mode 100644 sbt-app/src/sbt-test/java/method-handle-release/build.sbt
 create mode 100644 sbt-app/src/sbt-test/java/method-handle-release/src/main/scala/Main.scala
 create mode 100644 sbt-app/src/sbt-test/java/method-handle-release/test

diff --git a/sbt-app/src/sbt-test/java/method-handle-release/build.sbt b/sbt-app/src/sbt-test/java/method-handle-release/build.sbt
new file mode 100644
index 000000000..0cb11c5e3
--- /dev/null
+++ b/sbt-app/src/sbt-test/java/method-handle-release/build.sbt
@@ -0,0 +1,2 @@
+ThisBuild / scalaVersion := "2.13.16"
+scalacOptions += "-release:11"
diff --git a/sbt-app/src/sbt-test/java/method-handle-release/src/main/scala/Main.scala b/sbt-app/src/sbt-test/java/method-handle-release/src/main/scala/Main.scala
new file mode 100644
index 000000000..8c36d7268
--- /dev/null
+++ b/sbt-app/src/sbt-test/java/method-handle-release/src/main/scala/Main.scala
@@ -0,0 +1,19 @@
+import java.lang.invoke.{ MethodHandle, MethodHandles }
+
+object Main {
+  case class TestClass(number: Int)
+  def testMethod(): TestClass = {
+    TestClass(10)
+  }
+
+  def wrappedMethod(handle: MethodHandle): TestClass = {
+    handle.invokeExact()
+  }
+
+  def main(args: Array[String]): Unit = {
+    val method = classOf[Main.type].getDeclaredMethod("testMethod")
+    method.setAccessible(true)
+    val handle = MethodHandles.lookup.unreflect(method)
+    println(wrappedMethod(handle))
+  }
+}
diff --git a/sbt-app/src/sbt-test/java/method-handle-release/test b/sbt-app/src/sbt-test/java/method-handle-release/test
new file mode 100644
index 000000000..c0b8da542
--- /dev/null
+++ b/sbt-app/src/sbt-test/java/method-handle-release/test
@@ -0,0 +1,3 @@
+# https://github.com/sbt/sbt/issues/6175
+# MethodHandle.invokeExact fails to compile on JDK 15+ when targeting Java 11
+> compile