From e6666e4b1014ecc42f2a92298fb614c7eef781d7 Mon Sep 17 00:00:00 2001
From: eugene yokota <eed3si9n@gmail.com>
Date: Sat, 30 May 2026 20:16:58 -0400
Subject: [PATCH] [2.0.x] Fix duplicate autoplugins packageBin mappings (#9255)
 (#9273)

Deduplicate executable jar package entries. In the issue, the duplicate was something like:

(resource_managed/.../sbt/sbt.autoplugins, "sbt/sbt.autoplugins")
(classes/.../sbt/sbt.autoplugins,          "sbt/sbt.autoplugins")

This is because copyResources copied autoplugin metadata to the classes directory.

Solution: when composing the packageBinMappings, differentiate between artifacts that come from class directory and from outside of it. If there is a duplicate, prefer resource that comes from outside of it.

Co-authored-by: Anatolii Kmetiuk <anatoliykmetyuk@gmail.com>
---
 main/src/main/scala/sbt/Defaults.scala               | 12 ++++++++++--
 .../duplicate-autoplugins-packagebin/build.sbt       |  4 ++++
 .../src/main/scala/example/ScalacOptionsPlugin.scala |  5 +++++
 .../plugins/duplicate-autoplugins-packagebin/test    |  3 +++
 4 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/build.sbt
 create mode 100644 sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/scalac-options/src/main/scala/example/ScalacOptionsPlugin.scala
 create mode 100644 sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/test

diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index 888d42cdb..1273a3337 100644
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -1722,10 +1722,18 @@ object Defaults extends BuildCommon {
   def packageBinMappings: Initialize[Task[Seq[(HashedVirtualFileRef, String)]]] =
     Def.task {
       val converter = fileConverter.value
+      val classDirPath = classDirectory.value.toPath.toAbsolutePath.normalize
       val xs = products.value
-      xs
+      val allMappings = xs
         .flatMap(Path.allSubpaths)
-        .withFilter(_._1.isFile())
+        .filter(_._1.isFile())
+      val resourcePaths = allMappings.collect {
+        case (p, path) if !p.toPath.toAbsolutePath.normalize.startsWith(classDirPath) => path
+      }.toSet
+      allMappings
+        .filterNot { (p, path) =>
+          resourcePaths(path) && p.toPath.toAbsolutePath.normalize.startsWith(classDirPath)
+        }
         .map { (p, path) =>
           val vf = converter.toVirtualFile(p.toPath())
           (vf: HashedVirtualFileRef) -> path
diff --git a/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/build.sbt b/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/build.sbt
new file mode 100644
index 000000000..40734b4c1
--- /dev/null
+++ b/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/build.sbt
@@ -0,0 +1,4 @@
+ThisBuild / organization := "com.example"
+ThisBuild / version      := "0.1.0-SNAPSHOT"
+
+val `scalac-options` = project.enablePlugins(SbtPlugin)
diff --git a/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/scalac-options/src/main/scala/example/ScalacOptionsPlugin.scala b/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/scalac-options/src/main/scala/example/ScalacOptionsPlugin.scala
new file mode 100644
index 000000000..3d8f9eae2
--- /dev/null
+++ b/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/scalac-options/src/main/scala/example/ScalacOptionsPlugin.scala
@@ -0,0 +1,5 @@
+package example
+
+import sbt.*
+
+object ScalacOptionsPlugin extends AutoPlugin
diff --git a/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/test b/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/test
new file mode 100644
index 000000000..e00f9cbb0
--- /dev/null
+++ b/sbt-app/src/sbt-test/plugins/duplicate-autoplugins-packagebin/test
@@ -0,0 +1,3 @@
+> scalac-options / Compile / packageBin
+> scalac-options / Compile / copyResources
+> scalac-options / Compile / packageBin