From 1a6039c17a60525a9dcf825ad10fbe9e88da80f6 Mon Sep 17 00:00:00 2001
From: bitloi <raphaelaloi.eth@gmail.com>
Date: Sun, 1 Feb 2026 01:06:07 +0100
Subject: [PATCH] Handle ThisProject in aggregate and dependencies

Fixes #3616 - Scope's resolveProjectBuild and resolveProjectRef
mishandle ThisProject.

Previously, using ThisProject in aggregate() or dependsOn() would
cause a runtime error: 'Cannot resolve ThisProject w/o the current
project'.

This change adds proper handling for ThisProject in Load.scala:
- In checkAll: Skip validation for ThisProject (refers to self)
- In resolveProjects: Resolve ThisProject to ProjectRef(uri, p.id)
---
 main/src/main/scala/sbt/internal/Load.scala       |  2 ++
 .../project/thisProject-aggregate/build.sbt       | 15 +++++++++++++++
 .../sbt-test/project/thisProject-aggregate/test   |  3 +++
 3 files changed, 20 insertions(+)
 create mode 100644 sbt-app/src/sbt-test/project/thisProject-aggregate/build.sbt
 create mode 100644 sbt-app/src/sbt-test/project/thisProject-aggregate/test

diff --git a/main/src/main/scala/sbt/internal/Load.scala b/main/src/main/scala/sbt/internal/Load.scala
index 1bf7e4490..c89185e48 100755
--- a/main/src/main/scala/sbt/internal/Load.scala
+++ b/main/src/main/scala/sbt/internal/Load.scala
@@ -668,6 +668,7 @@ private[sbt] object Load {
     do
       ref match
         case LocalAggregate => ()
+        case ThisProject    => ()
         case _ =>
           val ProjectRef(refURI, refID) = Scope.resolveProjectRef(uri, rootProject, ref)
           val loadedUnit = builds(refURI)
@@ -714,6 +715,7 @@ private[sbt] object Load {
     val resolve: Project => ResolvedProject = (p: Project) =>
       p.resolve:
         case LocalAggregate => resolveAutoAggregate(uri, p, ps)
+        case ThisProject    => Vector(ProjectRef(uri, p.id))
         case ref            => Vector(Scope.resolveProjectRef(uri, rootProject, ref))
     LoadedBuildUnit(
       unit.unit,
diff --git a/sbt-app/src/sbt-test/project/thisProject-aggregate/build.sbt b/sbt-app/src/sbt-test/project/thisProject-aggregate/build.sbt
new file mode 100644
index 000000000..7240e2882
--- /dev/null
+++ b/sbt-app/src/sbt-test/project/thisProject-aggregate/build.sbt
@@ -0,0 +1,15 @@
+ThisBuild / scalaVersion := "2.13.16"
+
+lazy val root = project
+  .in(file("."))
+  .aggregate(ThisProject)
+  .settings(
+    name := "root-project"
+  )
+
+lazy val check = taskKey[Unit]("Verify ThisProject in aggregate works")
+
+root / check := {
+  val n = (root / name).value
+  assert(n == "root-project", s"Expected 'root-project' but got '$n'")
+}
diff --git a/sbt-app/src/sbt-test/project/thisProject-aggregate/test b/sbt-app/src/sbt-test/project/thisProject-aggregate/test
new file mode 100644
index 000000000..788d07bc3
--- /dev/null
+++ b/sbt-app/src/sbt-test/project/thisProject-aggregate/test
@@ -0,0 +1,3 @@
+# Verify that ThisProject in aggregate doesn't cause runtime error
+# This tests the fix for https://github.com/sbt/sbt/issues/3616
+> check