Set context classloader during Mill evaluation (#3940)

Seems to be necessary for some of the libraries people `import $ivy`, such as Guardrail
com-lihaoyi · Nov 11, 2024 · 67db6b5 · 67db6b5
1 parent a7d4813
commit 67db6b5
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/runner/src/mill/runner/MillBuildBootstrap.scala b/runner/src/mill/runner/MillBuildBootstrap.scala
@@ -407,8 +407,12 @@ object MillBuildBootstrap {
       targetsAndParams: Seq[String]
   ): (Either[String, Seq[Any]], Seq[Watchable], Seq[Watchable]) = {
     rootModule.evalWatchedValues.clear()
+    val previousClassloader = Thread.currentThread().getContextClassLoader
     val evalTaskResult =
-      RunScript.evaluateTasksNamed(evaluator, targetsAndParams, SelectMode.Separated)
+      try {
+        Thread.currentThread().setContextClassLoader(rootModule.getClass.getClassLoader)
+        RunScript.evaluateTasksNamed(evaluator, targetsAndParams, SelectMode.Separated)
+      } finally Thread.currentThread().setContextClassLoader(previousClassloader)
     val moduleWatched = rootModule.watchedValues.toVector
     val addedEvalWatched = rootModule.evalWatchedValues.toVector