Resolve references to @main-repo//foo to //foo

Bazel was creating an dummy external repository for @main-repo, which
doesn't work with package paths and will cause conflicts once
@main-repo//foo and //foo refer to the same path.

This adds a "soft pull" option to WorkspaceNameFunction: it can either
parse the entire WORKSPACE file to find the name or just the first section.
That way PackageLookupFunction can find the repository name without causing
a circular dependency.

This should have no change of behavior and is already tested in
https://github.com/bazelbuild/bazel/blob/master/src/test/shell/bazel/workspace_test.sh#L176.

PiperOrigin-RevId: 161536466

3 files changed, 63 insertions, 34 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
index c0a115ad6c..d264cea205 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
@@ -18,6 +18,7 @@ import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelValidator;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.packages.BuildFileNotFoundException;
 import com.google.devtools.build.lib.packages.ErrorDeterminingRepositoryException;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
@@ -294,8 +295,20 @@ public class PackageLookupFunction implements SkyFunction {
   private PackageLookupValue computeExternalPackageLookupValue(
       SkyKey skyKey, Environment env, PackageIdentifier packageIdentifier)
       throws PackageLookupFunctionException, InterruptedException {
+    // Check if this is the main repository.
     PackageIdentifier id = (PackageIdentifier) skyKey.argument();
-    SkyKey repositoryKey = RepositoryValue.key(id.getRepository());
+    RepositoryName repositoryName = id.getRepository();
+    WorkspaceNameValue workspaceNameValue = (WorkspaceNameValue)
+        env.getValue(WorkspaceNameValue.firstChunk());
+    if (workspaceNameValue == null) {
+      return null;
+    }
+    if (repositoryName.strippedName().equals(workspaceNameValue.getName())) {
+      return (PackageLookupValue) env.getValue(PackageLookupValue.key(
+          PackageIdentifier.createInMainRepo(id.getPackageFragment())));
+    }
+    // Otherwise look up the repository.
+    SkyKey repositoryKey = RepositoryValue.key(repositoryName);
     RepositoryValue repositoryValue;
     try {
       repositoryValue = (RepositoryValue) env.getValueOrThrow(
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceNameFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceNameFunction.java
index 9284f5c2e9..4582572c4a 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceNameFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceNameFunction.java
@@ -14,9 +14,11 @@
 package com.google.devtools.build.lib.skyframe;
 
 import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.packages.BuildFileContainsErrorsException;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.packages.Package;
+import com.google.devtools.build.lib.vfs.RootedPath;
 import com.google.devtools.build.skyframe.SkyFunction;
 import com.google.devtools.build.skyframe.SkyFunctionException;
 import com.google.devtools.build.skyframe.SkyKey;
@@ -34,18 +36,47 @@ public class WorkspaceNameFunction implements SkyFunction {
   @Nullable
   public SkyValue compute(SkyKey skyKey, Environment env)
       throws InterruptedException, WorkspaceNameFunctionException {
-    SkyKey externalPackageKey = PackageValue.key(Label.EXTERNAL_PACKAGE_IDENTIFIER);
-    PackageValue externalPackageValue = (PackageValue) env.getValue(externalPackageKey);
-    if (externalPackageValue == null) {
+    boolean firstChunk = (boolean) skyKey.argument();
+    Package externalPackage = firstChunk ? firstChunk(env) : parseFullPackage(env);
+    if (externalPackage == null) {
       return null;
     }
-    Package externalPackage = externalPackageValue.getPackage();
     if (externalPackage.containsErrors()) {
+      Event.replayEventsOn(env.getListener(), externalPackage.getEvents());
       throw new WorkspaceNameFunctionException();
     }
     return WorkspaceNameValue.withName(externalPackage.getWorkspaceName());
   }
 
+  /**
+   * This just examines the first chunk of the WORKSPACE file to avoid circular dependencies and
+   * overeager invalidation during package loading.
+   */
+  private Package firstChunk(Environment env) throws InterruptedException {
+    SkyKey packageLookupKey = PackageLookupValue.key(Label.EXTERNAL_PACKAGE_IDENTIFIER);
+    PackageLookupValue packageLookupValue = (PackageLookupValue) env.getValue(packageLookupKey);
+    if (packageLookupValue == null) {
+      return null;
+    }
+    RootedPath workspacePath = packageLookupValue.getRootedPath(Label.EXTERNAL_PACKAGE_IDENTIFIER);
+
+    SkyKey workspaceKey = WorkspaceFileValue.key(workspacePath);
+    WorkspaceFileValue value = (WorkspaceFileValue) env.getValue(workspaceKey);
+    if (value == null) {
+      return null;
+    }
+    return value.getPackage();
+  }
+
+  private Package parseFullPackage(Environment env) throws InterruptedException {
+    SkyKey externalPackageKey = PackageValue.key(Label.EXTERNAL_PACKAGE_IDENTIFIER);
+    PackageValue externalPackageValue = (PackageValue) env.getValue(externalPackageKey);
+    if (externalPackageValue == null) {
+      return null;
+    }
+    return externalPackageValue.getPackage();
+  }
+
   @Override
   @Nullable
   public String extractTag(SkyKey skyKey) {
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceNameValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceNameValue.java
index 4da943b6ab..98fe8b2416 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceNameValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceNameValue.java
@@ -28,9 +28,6 @@ import java.util.Objects;
  * the WORKSPACE file.
  */
 public class WorkspaceNameValue implements SkyValue {
-  private static final SkyKey KEY =
-      LegacySkyKey.create(SkyFunctions.WORKSPACE_NAME, DummyArgument.INSTANCE);
-
   private final String workspaceName;
 
   private WorkspaceNameValue(String workspaceName) {
@@ -44,9 +41,21 @@ public class WorkspaceNameValue implements SkyValue {
     return workspaceName;
   }
 
-  /** Returns the (singleton) {@link SkyKey} for {@link WorkspaceNameValue}s. */
+  /** Returns the {@link SkyKey} for {@link WorkspaceNameValue}s. */
   public static SkyKey key() {
-    return KEY;
+    return createKey(false);
+  }
+
+  /**
+   * Returns the {@link SkyKey} for a less-aggressive {@link WorkspaceNameValue} query, when
+   * we don't want to parse the whole WORKSPACE file.
+   */
+  public static SkyKey firstChunk() {
+    return createKey(true);
+  }
+
+  private static SkyKey createKey(boolean firstChunk) {
+    return LegacySkyKey.create(SkyFunctions.WORKSPACE_NAME, firstChunk);
   }
 
   /** Returns a {@link WorkspaceNameValue} for a workspace with the given name. */
@@ -72,28 +81,4 @@ public class WorkspaceNameValue implements SkyValue {
   public String toString() {
     return String.format("WorkspaceNameValue[name=%s]", workspaceName);
   }
-
-  /** Singleton class used as the {@link SkyKey#argument} for {@link WorkspaceNameValue#key}. */
-  public static final class DummyArgument {
-    static final int HASHCODE = DummyArgument.class.getCanonicalName().hashCode();
-    public static final DummyArgument INSTANCE = new DummyArgument();
-
-    private DummyArgument() {
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-      return obj instanceof DummyArgument;
-    }
-
-    @Override
-    public int hashCode() {
-      return HASHCODE;
-    }
-
-    @Override
-    public String toString() {
-      return "#";
-    }
-  }
 }