merged

Author: lihaoyi

core/exec/src/mill/exec/GroupExecution.scala

@@ -230,7 +230,10 @@ trait GroupExecution {
       exclusive: Boolean,
       upstreamPathRefs: Seq[PathRef]
   ): GroupExecution.Results = {
-    val sideHashes = group.iterator.map(_.sideHash).sum
+    val (sideHashes, hasSideEffects) = group.iterator.foldLeft((0, false)) { case ((sum, has), t) =>
+      val sideHash = t.sideHash
+      (sum + sideHash, has || sideHash != 0)
+    }
 
     val inputsHash = {
       val externalInputsHash = MurmurHash3.orderedHash(
@@ -280,7 +283,7 @@ trait GroupExecution {
         // Helper to evaluate the task with full caching support
         def evaluateTaskWithCaching(): GroupExecution.Results = {
           val cached = Option
-            .when(sideHashes == 0) { loadCachedJson(logger, inputsHash, labelled, paths) }
+            .when(!hasSideEffects) { loadCachedJson(logger, inputsHash, labelled, paths) }
             .flatten
 
           // `cached.isEmpty` means worker metadata file removed by user so recompute the worker
@@ -714,7 +717,7 @@ trait GroupExecution {
   def getValueHash(v: Val, task: Task[?], inputsHash: Int): Int = {
     if (task.isInstanceOf[Task.Worker[?]]) inputsHash
     else {
-      task match {
+      val base = task match {
         case named: Task.Named[_] =>
           named.writerOpt match {
             case Some(writer) =>
@@ -725,6 +728,7 @@ trait GroupExecution {
           }
         case _ => v.##
       }
+      base + invalidateAllHashes
     }
   }
 

core/internal/src/mill/internal/MillPathSerializer.scala

@@ -1,13 +1,27 @@
 package mill.internal
 
-import java.nio.file.Files
+import java.nio.file.{Files, LinkOption}
 
 object MillPathSerializer {
   def setupSymlinks(wd: os.Path, workspace: os.Path): Unit = {
     for ((base, link) <- defaultMapping(workspace)) {
-      os.makeDir.all(wd / link / "..")
-      os.remove(wd / link)
-      Files.createSymbolicLink((wd / link).toNIO, base.wrapped)
+      val target = wd / link
+      val targetNio = target.toNIO
+      os.makeDir.all(target / "..")
+
+      if (Files.isSymbolicLink(targetNio)) {
+        val currentTarget = Files.readSymbolicLink(targetNio)
+        if (currentTarget != base.wrapped) {
+          os.remove(target)
+          Files.createSymbolicLink(targetNio, base.wrapped)
+        }
+      } else if (Files.exists(targetNio, LinkOption.NOFOLLOW_LINKS)) {
+        throw new IllegalStateException(
+          s"Refusing to overwrite non-symlink path required for path serialization: $target"
+        )
+      } else {
+        Files.createSymbolicLink(targetNio, base.wrapped)
+      }
     }
   }
 

runner/daemon/src/mill/daemon/MillBuildBootstrap.scala

@@ -209,18 +209,30 @@ class MillBuildBootstrap(
       // by codesig analysis, not by classLoaderSigHash.
       millClassloaderSigHash = nestedState.frames.headOption match {
         case Some(frame) =>
+          def stablePathId(path: os.Path): String = {
+            if (path.startsWith(currentRoot)) s"<workspace>/${path.subRelativeTo(currentRoot)}"
+            else if (path.startsWith(os.home)) s"<home>/${path.subRelativeTo(os.home)}"
+            else path.toString
+          }
+
           val compileDestPath = frame.compileOutput.map(p => os.Path(p.javaPath))
           frame.runClasspath
             .filter { p =>
               val path = os.Path(p.javaPath)
               !compileDestPath.contains(path) &&
               !path.toString.contains("generatedScriptSources.dest")
             }
-            .map(p => (os.Path(p.javaPath), p.sig))
+            .map(p => (stablePathId(os.Path(p.javaPath)), p.sig))
             .hashCode()
         case None =>
           millBootClasspathPathRefs
-            .map(p => (os.Path(p.javaPath), p.sig))
+            .map { p =>
+              val path = os.Path(p.javaPath)
+              val stable =
+                if (path.startsWith(os.home)) s"<home>/${path.subRelativeTo(os.home)}"
+                else path.toString
+              (stable, p.sig)
+            }
             .hashCode()
       },
       millClassloaderIdentityHash = nestedState