Make RedirectChaser follow redirects through external repositories correctly and implement a "@//" label syntax that always points to the main repository.

--
MOS_MIGRATED_REVID=105041493

3 files changed, 19 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RedirectChaser.java b/src/main/java/com/google/devtools/build/lib/analysis/RedirectChaser.java
index 946f2a9427..d6c6ab3b46 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RedirectChaser.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RedirectChaser.java
@@ -92,6 +92,7 @@ public final class RedirectChaser {
           return label;
         }
 
+        newLabel = label.resolveRepositoryRelative(newLabel);
         label = newLabel;
         if (!visitedLabels.add(label)) {
           throw new InvalidConfigurationException("The " + name + " points to a filegroup which "
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelConfigurationCollection.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelConfigurationCollection.java
index 5f31945bfb..8ab04b3694 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelConfigurationCollection.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelConfigurationCollection.java
@@ -278,10 +278,12 @@ public class BazelConfigurationCollection implements ConfigurationCollectionFact
         // not necessarily the configuration actually applied to the rule. We should correlate the
         // two. However, doing so requires faithfully reflecting the configuration transitions that
         // might happen as we traverse the dependency chain.
+        // TODO(bazel-team): Why don't we use AbstractAttributeMapper#visitLabels() here?
         for (List<Label> labelsForConfiguration :
             AggregatingAttributeMapper.of(rule).visitAttribute("srcs", BuildType.LABEL_LIST)) {
           for (Label label : labelsForConfiguration) {
-            collectTransitiveClosure(packageProvider, reachableLabels, label);
+            collectTransitiveClosure(packageProvider, reachableLabels,
+                from.resolveRepositoryRelative(label));
           }
         }
       }
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
index f7126ae769..fc3c3bba7c 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
@@ -41,6 +41,7 @@ import java.io.Serializable;
 @SkylarkModule(name = "Label", doc = "A BUILD target identifier.")
 @Immutable @ThreadSafe
 public final class Label implements Comparable<Label>, Serializable, SkylarkPrintableValue {
+  private static final PathFragment EXTERNAL = new PathFragment("external");
 
   /**
    * Factory for Labels from absolute string form. e.g.
@@ -352,8 +353,21 @@ public final class Label implements Comparable<Label>, Serializable, SkylarkPrin
    * repository would point back to the main repository, which is usually not what is intended.
    */
   public Label resolveRepositoryRelative(Label relative) {
+    if (relative.packageIdentifier.getRepository().getName().equals("@")) {
+      try {
+        return new Label(
+            PackageIdentifier.create(
+                PackageIdentifier.DEFAULT_REPOSITORY_NAME,
+                relative.packageIdentifier.getPackageFragment()),
+            relative.getName());
+      } catch (LabelSyntaxException e) {
+        throw new IllegalStateException(e);
+      }
+    }
+
     if (packageIdentifier.getRepository().isDefault()
-        || !relative.packageIdentifier.getRepository().isDefault()) {
+        || !relative.packageIdentifier.getRepository().isDefault()
+        || relative.packageIdentifier.getPackageFragment().equals(EXTERNAL)) {
       return relative;
     } else {
       try {