1 files changed, 80 insertions, 13 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 8f5351fd8c..875e89ff74 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
@@ -358,10 +358,10 @@ public final class RuleContext extends TargetContext
   @Override
   public void attributeError(String attrName, String message) {
     reportError(rule.getAttributeLocation(attrName),
-                prefixAttributeMessage(Attribute.isImplicit(attrName)
-                                           ? "(an implicit dependency)"
-                                           : attrName,
-                                       message));
+        prefixAttributeMessage(Attribute.isImplicit(attrName)
+                ? "(an implicit dependency)"
+                : attrName,
+            message));
   }
 
   /**
@@ -373,10 +373,10 @@ public final class RuleContext extends TargetContext
   @Override
   public void attributeWarning(String attrName, String message) {
     reportWarning(rule.getAttributeLocation(attrName),
-                  prefixAttributeMessage(Attribute.isImplicit(attrName)
-                                             ? "(an implicit dependency)"
-                                             : attrName,
-                                         message));
+        prefixAttributeMessage(Attribute.isImplicit(attrName)
+                ? "(an implicit dependency)"
+                : attrName,
+            message));
   }
 
   private String prefixAttributeMessage(String attrName, String message) {
@@ -424,8 +424,12 @@ public final class RuleContext extends TargetContext
    * signature.
    */
   private Artifact internalCreateOutputArtifact(Target target) {
+    Preconditions.checkState(
+        target.getLabel().getPackageIdentifier().equals(getLabel().getPackageIdentifier()),
+        "Creating output artifact for target '%s' in different package than the rule '%s' "
+            + "being analyzed", target.getLabel(), getLabel());
     Root root = getBinOrGenfilesDirectory();
-    return getAnalysisEnvironment().getDerivedArtifact(Util.getWorkspaceRelativePath(target), root);
+    return getPackageRelativeArtifact(target.getName(), root);
   }
 
   /**
@@ -440,6 +444,71 @@ public final class RuleContext extends TargetContext
         : getConfiguration().getGenfilesDirectory();
   }
 
+  /**
+   * Creates an artifact in a directory that is unique to the package that contains the rule,
+   * thus guaranteeing that it never clashes with artifacts created by rules in other packages.
+   */
+  public Artifact getPackageRelativeArtifact(String relative, Root root) {
+    return getPackageRelativeArtifact(new PathFragment(relative), root);
+  }
+
+  /**
+   * Creates an artifact in a directory that is unique to the package that contains the rule,
+   * thus guaranteeing that it never clashes with artifacts created by rules in other packages.
+   */
+  public Artifact getPackageRelativeArtifact(PathFragment relative, Root root) {
+    return getDerivedArtifact(getPackageDirectory().getRelative(relative), root);
+  }
+
+  /**
+   * Returns the root-relative path fragment under which output artifacts of this rule should go.
+   *
+   * <p>Note that:
+   * <ul>
+   *   <li>This doesn't guarantee that there are no clashes with rules in the same package.
+   *   <li>If possible, {@link #getPackageRelativeArtifact(PathFragment, Root)} should be used
+   *   instead of this method.
+   * </ul>
+   *
+   * Ideally, user-visible artifacts should all have corresponding output file targets, all others
+   * should go into a rule-specific directory.
+   * {@link #getUniqueDirectoryArtifact(String, PathFragment, Root)}) ensures that this is the case.
+   */
+  public PathFragment getPackageDirectory() {
+    return getLabel().getPackageIdentifier().getPathFragment();
+  }
+
+  /**
+   * Creates an artifact under a given root with the given root-relative path.
+   *
+   * <p>Verifies that it is in the root-relative directory corresponding to the package of the rule,
+   * thus ensuring that it doesn't clash with other artifacts generated by other rules using this
+   * method.
+   */
+  public Artifact getDerivedArtifact(PathFragment rootRelativePath, Root root) {
+    Preconditions.checkState(rootRelativePath.startsWith(getPackageDirectory()),
+        "Output artifact '%s' not under package directory '%s' for target '%s'",
+        rootRelativePath, getPackageDirectory(), getLabel());
+    return getAnalysisEnvironment().getDerivedArtifact(rootRelativePath, root);
+  }
+  /**
+   * Creates an artifact in a directory that is unique to the rule, thus guaranteeing that it never
+   * clashes with artifacts created by other rules.
+   */
+  public Artifact getUniqueDirectoryArtifact(
+      String uniqueDirectory, String relative, Root root) {
+    return getUniqueDirectoryArtifact(uniqueDirectory, new PathFragment(relative), root);
+  }
+
+  public Artifact getUniqueDirectoryArtifact(
+      String uniqueDirectory, PathFragment relative, Root root) {
+    return getDerivedArtifact(getUniqueDirectory(uniqueDirectory).getRelative(relative), root);
+  }
+
+  public PathFragment getArtifactPackagePrefix() {
+    return getLabel().getPackageIdentifier().getPathFragment();
+  }
+
   private Attribute getAttribute(String attributeName) {
     // TODO(bazel-team): We should check original rule for such attribute first, because aspect
     // can't contain empty attribute. Consider changing type of prerequisiteMap from
@@ -982,9 +1051,7 @@ public final class RuleContext extends TargetContext
    * Only use from Skylark. Returns the implicit output artifact for a given output path.
    */
   public Artifact getImplicitOutputArtifact(String path) {
-    Root root = getBinOrGenfilesDirectory();
-    PathFragment packageFragment = getLabel().getPackageFragment();
-    return getAnalysisEnvironment().getDerivedArtifact(packageFragment.getRelative(path), root);
+    return getPackageRelativeArtifact(path, getBinOrGenfilesDirectory());
   }
 
   /**
@@ -1061,7 +1128,7 @@ public final class RuleContext extends TargetContext
    */
   public final Artifact getRelatedArtifact(PathFragment pathFragment, String extension) {
     PathFragment file = FileSystemUtils.replaceExtension(pathFragment, extension);
-    return getAnalysisEnvironment().getDerivedArtifact(file, getConfiguration().getBinDirectory());
+    return getDerivedArtifact(file, getConfiguration().getBinDirectory());
   }
 
   /**