Bzlmod: When evaluating extensions in the main repo, do not load WORKSPACE

(bazelbuild#13316)

See new comment in BzlLoadFunction.java for details. bazelbuild/bazel-central-registry#47 (comment) also has a bit more context.

PiperOrigin-RevId: 417633822

Author: Wyverald

src/main/java/com/google/devtools/build/lib/skyframe/BUILD

@@ -2207,6 +2207,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib/concurrent",
         "//src/main/java/com/google/devtools/build/lib/skyframe/serialization/autocodec",
         "//src/main/java/com/google/devtools/build/skyframe:skyframe-objects",
+        "//third_party:auto_value",
         "//third_party:guava",
     ],
 )

src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java

@@ -29,6 +29,7 @@
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.cmdline.RepositoryMapping;
+import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
@@ -813,6 +814,7 @@ private static RepositoryMapping getRepositoryMapping(BzlLoadValue.Key key, Envi
     }
 
     Label enclosingFileLabel = key.getLabel();
+    RepositoryName repoName = enclosingFileLabel.getRepository();
 
     if (key instanceof BzlLoadValue.KeyForWorkspace) {
       // Still during workspace file evaluation
@@ -828,30 +830,41 @@ private static RepositoryMapping getRepositoryMapping(BzlLoadValue.Key key, Envi
         // Note: we know for sure that the requested WorkspaceFileValue is fully computed so we do
         // not need to check if it is null
         return RepositoryMapping.createAllowingFallback(
-            workspaceFileValue
-                .getRepositoryMapping()
-                .getOrDefault(enclosingFileLabel.getRepository(), ImmutableMap.of()));
+            workspaceFileValue.getRepositoryMapping().getOrDefault(repoName, ImmutableMap.of()));
         // NOTE(wyv): this means that, in the WORKSPACE file, we can't load from a repo generated by
         // bzlmod. If that's a problem, we should "fall back" to the bzlmod case below.
       }
     }
 
-    if (key instanceof BzlLoadValue.KeyForBzlmod
-        && enclosingFileLabel.getRepository().getName().equals("bazel_tools")) {
-      // Special case: we're only here to get the @bazel_tools repo (for example, for http_archive).
-      // This repo shouldn't have visibility into anything else (during repo generation), so we just
-      // return an empty repo mapping.
-      // TODO(wyv): disallow fallback.
-      return RepositoryMapping.ALWAYS_FALLBACK;
+    if (key instanceof BzlLoadValue.KeyForBzlmod) {
+      if (repoName.equals(RepositoryName.BAZEL_TOOLS)) {
+        // Special case: we're only here to get the @bazel_tools repo (for example, for
+        // http_archive). This repo shouldn't have visibility into anything else (during repo
+        // generation), so we just return an empty repo mapping.
+        // TODO(wyv): disallow fallback.
+        return RepositoryMapping.ALWAYS_FALLBACK;
+      }
+      if (repoName.isMain()) {
+        // Special case: when we try to run an extension in the main repo, we need to grab the repo
+        // mapping for the main repo, which normally would include all WORKSPACE repos. This is
+        // problematic if the reason we're running an extension at all is that we're trying to do a
+        // `load` in WORKSPACE. So we specifically say that, to run an extension in the main repo,
+        // we ask for a repo mapping *without* WORKSPACE repos.
+        RepositoryMappingValue repositoryMappingValue =
+            (RepositoryMappingValue)
+                env.getValue(RepositoryMappingValue.KEY_FOR_ROOT_MODULE_WITHOUT_WORKSPACE_REPOS);
+        if (repositoryMappingValue == null) {
+          return null;
+        }
+        return repositoryMappingValue.getRepositoryMapping();
+      }
     }
 
     // This is either a .bzl loaded from BUILD files, or a .bzl loaded for bzlmod (in which case the
     // .bzl file *has* to be from a Bazel module anyway). So we can just use the full repo mapping
     // from RepositoryMappingFunction.
-    PackageIdentifier packageIdentifier = enclosingFileLabel.getPackageIdentifier();
     RepositoryMappingValue repositoryMappingValue =
-        (RepositoryMappingValue)
-            env.getValue(RepositoryMappingValue.key(packageIdentifier.getRepository()));
+        (RepositoryMappingValue) env.getValue(RepositoryMappingValue.key(repoName));
     if (repositoryMappingValue == null) {
       return null;
     }

src/main/java/com/google/devtools/build/lib/skyframe/RepositoryMappingFunction.java

@@ -46,7 +46,7 @@ public class RepositoryMappingFunction implements SkyFunction {
   @Override
   public SkyValue compute(SkyKey skyKey, Environment env)
       throws SkyFunctionException, InterruptedException {
-    RepositoryName repositoryName = (RepositoryName) skyKey.argument();
+    RepositoryName repositoryName = ((RepositoryMappingValue.Key) skyKey).repoName();
 
     BazelModuleResolutionValue bazelModuleResolutionValue = null;
     if (Preconditions.checkNotNull(RepositoryDelegatorFunction.ENABLE_BZLMOD.get(env))) {
@@ -56,9 +56,10 @@ public SkyValue compute(SkyKey skyKey, Environment env)
         return null;
       }
 
-      // The root module should be able to see repos defined in WORKSPACE. Therefore, we find all
-      // workspace repos and add them as extra visible repos in root module's repo mappings.
-      if (repositoryName.isMain()) {
+      if (repositoryName.isMain()
+          && ((RepositoryMappingValue.Key) skyKey).rootModuleShouldSeeWorkspaceRepos()) {
+        // The root module should be able to see repos defined in WORKSPACE. Therefore, we find all
+        // workspace repos and add them as extra visible repos in root module's repo mappings.
         SkyKey externalPackageKey = PackageValue.key(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER);
         PackageValue externalPackageValue = (PackageValue) env.getValue(externalPackageKey);
         if (env.valuesMissing()) {

src/main/java/com/google/devtools/build/lib/skyframe/RepositoryMappingValue.java

@@ -14,14 +14,15 @@
 
 package com.google.devtools.build.lib.skyframe;
 
+import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Interner;
 import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
-import com.google.devtools.build.skyframe.AbstractSkyKey;
 import com.google.devtools.build.skyframe.SkyFunctionName;
+import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
 import java.util.Objects;
 
@@ -48,6 +49,8 @@
  * packages. If the mappings are changed then the external packages need to be reloaded.
  */
 public class RepositoryMappingValue implements SkyValue {
+  public static final Key KEY_FOR_ROOT_MODULE_WITHOUT_WORKSPACE_REPOS =
+      Key.create(RepositoryName.MAIN, /*rootModuleShouldSeeWorkspaceRepos=*/ false);
 
   private final RepositoryMapping repositoryMapping;
 
@@ -63,7 +66,8 @@ public RepositoryMapping getRepositoryMapping() {
 
   /** Returns the {@link Key} for {@link RepositoryMappingValue}s. */
   public static Key key(RepositoryName repositoryName) {
-    return RepositoryMappingValue.Key.create(repositoryName);
+    return RepositoryMappingValue.Key.create(
+        repositoryName, /*rootModuleShouldSeeWorkspaceRepos=*/ true);
   }
 
   /** Returns a {@link RepositoryMappingValue} for a workspace with the given name. */
@@ -90,21 +94,25 @@ public String toString() {
     return repositoryMapping.toString();
   }
 
-  /** {@link com.google.devtools.build.skyframe.SkyKey} for {@link RepositoryMappingValue}. */
-  @AutoCodec.VisibleForSerialization
-  @AutoCodec
-  static class Key extends AbstractSkyKey<RepositoryName> {
+  /** {@link SkyKey} for {@link RepositoryMappingValue}. */
+  @AutoValue
+  abstract static class Key implements SkyKey {
 
     private static final Interner<Key> interner = BlazeInterners.newWeakInterner();
 
-    private Key(RepositoryName arg) {
-      super(arg);
-    }
+    /** The name of the repo to grab mappings for. */
+    abstract RepositoryName repoName();
+
+    /**
+     * Whether the root module should see repos defined in WORKSPACE. This only takes effect when
+     * {@link #repoName} is the main repo.
+     */
+    abstract boolean rootModuleShouldSeeWorkspaceRepos();
 
-    @AutoCodec.VisibleForSerialization
     @AutoCodec.Instantiator
-    static Key create(RepositoryName arg) {
-      return interner.intern(new Key(arg));
+    static Key create(RepositoryName repoName, boolean rootModuleShouldSeeWorkspaceRepos) {
+      return interner.intern(
+          new AutoValue_RepositoryMappingValue_Key(repoName, rootModuleShouldSeeWorkspaceRepos));
     }
 
     @Override

src/test/java/com/google/devtools/build/lib/skyframe/RepositoryMappingFunctionTest.java

@@ -103,8 +103,7 @@ public RepositoryMappingValue withMappingForRootModule(
 
   @Test
   public void testSimpleMapping() throws Exception {
-    scratch.overwriteFile(
-        "WORKSPACE",
+    rewriteWorkspace(
         "workspace(name = 'good')",
         "local_repository(",
         "    name = 'a_remote_repo',",
@@ -316,8 +315,7 @@ public void testRepoNameMapping_multipleVersionOverride_lookup() throws Exceptio
 
   @Test
   public void testMultipleRepositoriesWithMapping() throws Exception {
-    scratch.overwriteFile(
-        "WORKSPACE",
+    rewriteWorkspace(
         "workspace(name = 'good')",
         "local_repository(",
         "    name = 'a_remote_repo',",
@@ -356,8 +354,7 @@ public void testMultipleRepositoriesWithMapping() throws Exception {
 
   @Test
   public void testRepositoryWithMultipleMappings() throws Exception {
-    scratch.overwriteFile(
-        "WORKSPACE",
+    rewriteWorkspace(
         "workspace(name = 'good')",
         "local_repository(",
         "    name = 'a_remote_repo',",
@@ -381,9 +378,8 @@ public void testRepositoryWithMultipleMappings() throws Exception {
   }
 
   @Test
-  public void testMixtureOfBothSystems() throws Exception {
-    scratch.overwriteFile(
-        "WORKSPACE",
+  public void testMixtureOfBothSystems_workspaceRepo() throws Exception {
+    rewriteWorkspace(
         "workspace(name = 'root')",
         "local_repository(",
         "    name = 'ws_repo',",
@@ -433,6 +429,72 @@ public void testMixtureOfBothSystems() throws Exception {
                     .build()));
   }
 
+  @Test
+  public void testMixtureOfBothSystems_mainRepo() throws Exception {
+    rewriteWorkspace(
+        "workspace(name = 'root')",
+        "local_repository(",
+        "    name = 'ws_repo',",
+        "    path = '/ws_repo',",
+        ")");
+    scratch.overwriteFile(
+        "MODULE.bazel", "module(name='A',version='0.1')", "bazel_dep(name='B',version='1.0')");
+    registry
+        .addModule(
+            createModuleKey("B", "1.0"),
+            "module(name='B', version='1.0');bazel_dep(name='C', version='2.0')")
+        .addModule(createModuleKey("C", "2.0"), "module(name='C', version='2.0')");
+
+    SkyKey skyKey = RepositoryMappingValue.key(RepositoryName.MAIN);
+    assertThatEvaluationResult(eval(skyKey))
+        .hasEntryThat(skyKey)
+        .isEqualTo(
+            withMappingForRootModule(
+                ImmutableMap.of(
+                    RepositoryName.MAIN,
+                    RepositoryName.MAIN,
+                    RepositoryName.create("A"),
+                    RepositoryName.MAIN,
+                    RepositoryName.create("B"),
+                    RepositoryName.create("B.1.0"),
+                    RepositoryName.create("root"),
+                    RepositoryName.create("root"),
+                    RepositoryName.create("ws_repo"),
+                    RepositoryName.create("ws_repo")),
+                RepositoryName.MAIN));
+  }
+
+  @Test
+  public void testMixtureOfBothSystems_mainRepo_shouldNotSeeWorkspaceRepos() throws Exception {
+    rewriteWorkspace(
+        "workspace(name = 'root')",
+        "local_repository(",
+        "    name = 'ws_repo',",
+        "    path = '/ws_repo',",
+        ")");
+    scratch.overwriteFile(
+        "MODULE.bazel", "module(name='A',version='0.1')", "bazel_dep(name='B',version='1.0')");
+    registry
+        .addModule(
+            createModuleKey("B", "1.0"),
+            "module(name='B', version='1.0');bazel_dep(name='C', version='2.0')")
+        .addModule(createModuleKey("C", "2.0"), "module(name='C', version='2.0')");
+
+    SkyKey skyKey = RepositoryMappingValue.KEY_FOR_ROOT_MODULE_WITHOUT_WORKSPACE_REPOS;
+    assertThatEvaluationResult(eval(skyKey))
+        .hasEntryThat(skyKey)
+        .isEqualTo(
+            withMapping(
+                ImmutableMap.of(
+                    RepositoryName.MAIN,
+                    RepositoryName.MAIN,
+                    RepositoryName.create("A"),
+                    RepositoryName.MAIN,
+                    RepositoryName.create("B"),
+                    RepositoryName.create("B.1.0")),
+                RepositoryName.MAIN));
+  }
+
   @Test
   public void testErrorWithMapping() throws Exception {
     reporter.removeHandler(failFastHandler);