1 files changed, 15 insertions, 1 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
index 656ca2595f..4efcf035ac 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
@@ -87,6 +87,7 @@ import com.google.devtools.build.lib.util.OrderedSetMultimap;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.util.StringUtil;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
+import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -592,6 +593,19 @@ public final class RuleContext extends TargetContext
    * thus guaranteeing that it never clashes with artifacts created by rules in other packages.
    */
   public Artifact getPackageRelativeArtifact(PathFragment relative, Root root) {
+    // TODO: other root types, is this never a main repo?
+    if (relative.startsWith(new PathFragment(Label.EXTERNAL_PATH_PREFIX))) {
+      // This is an external path, use a different root.
+      if (root.isSourceRoot()) {
+        root = Root.asSourceRoot(root.getPath().getRelative(relative.subFragment(0, 2)));
+      } else {
+        boolean isMainRepo = false;
+        Path newExecRoot = root.getExecRoot().getRelative(relative.subFragment(0, 2));
+        root = Root.asDerivedRoot(
+            newExecRoot, newExecRoot.getRelative(root.getExecPath()), isMainRepo);
+      }
+      relative = relative.subFragment(2, relative.segmentCount());
+    }
     return getDerivedArtifact(getPackageDirectory().getRelative(relative), root);
   }
 
@@ -610,7 +624,7 @@ public final class RuleContext extends TargetContext
    * {@link #getUniqueDirectoryArtifact(String, PathFragment, Root)}) ensures that this is the case.
    */
   public PathFragment getPackageDirectory() {
-    return getLabel().getPackageIdentifier().getSourceRoot();
+    return getLabel().getPackageIdentifier().getPackageFragment();
   }
 
   /**