Address review comment

Author: fmeum

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

@@ -65,7 +65,6 @@
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Consumer;
 import javax.annotation.Nullable;
@@ -763,7 +762,7 @@ private BzlLoadValue computeInternalWithCompiledBzl(
     if (repoMapping == null) {
       return null;
     }
-    Optional<RepositoryMapping> mainRepoMapping =
+    RepositoryMapping mainRepoMapping =
         getMainRepositoryMapping(key, builtins.starlarkSemantics, env);
     if (mainRepoMapping == null) {
       return null;
@@ -846,7 +845,7 @@ private BzlLoadValue computeInternalWithCompiledBzl(
         BazelModuleContext.create(
             label,
             repoMapping,
-            mainRepoMapping.orElse(null),
+            mainRepoMapping,
             prog.getFilename(),
             ImmutableList.copyOf(loadMap.values()),
             transitiveDigest);
@@ -980,30 +979,29 @@ private static RepositoryMapping getRepositoryMapping(
   }
 
   @Nullable
-  private static Optional<RepositoryMapping> getMainRepositoryMapping(
+  private static RepositoryMapping getMainRepositoryMapping(
       BzlLoadValue.Key key, StarlarkSemantics starlarkSemantics, Environment env)
       throws InterruptedException {
-    if (!starlarkSemantics.getBool(BuildLanguageOptions.ENABLE_BZLMOD)) {
-      return Optional.empty();
-    }
+    boolean bzlmod = starlarkSemantics.getBool(BuildLanguageOptions.ENABLE_BZLMOD);
     RepositoryMappingValue.Key repoMappingKey;
     if (key instanceof BzlLoadValue.KeyForBuild) {
       repoMappingKey = RepositoryMappingValue.key(RepositoryName.MAIN);
     } else if ((key instanceof BzlLoadValue.KeyForBzlmod
             && !(key instanceof BzlLoadValue.KeyForBzlmodBootstrap))
-        || key instanceof BzlLoadValue.KeyForWorkspace) {
+        || (bzlmod && key instanceof BzlLoadValue.KeyForWorkspace)) {
       // Since the main repo mapping requires evaluating WORKSPACE, but WORKSPACE can load from
       // extension repos, requesting the full main repo mapping would cause a cycle.
       repoMappingKey = RepositoryMappingValue.KEY_FOR_ROOT_MODULE_WITHOUT_WORKSPACE_REPOS;
     } else {
-      // Builtins and Bzlmod bootstrap repo rules don't need the main repo mapping.
-      return Optional.empty();
+      // For builtins, @bazel_tools, and legacy WORKSPACE, the key's local repo mapping can be used
+      // as the main repo mapping.
+      return getRepositoryMapping(key, starlarkSemantics, env);
     }
     var mainRepositoryMappingValue = (RepositoryMappingValue) env.getValue(repoMappingKey);
     if (mainRepositoryMappingValue == null) {
       return null;
     }
-    return Optional.of(mainRepositoryMappingValue.getRepositoryMapping());
+    return mainRepositoryMappingValue.getRepositoryMapping();
   }
 
   /**

src/test/shell/bazel/starlark_repository_test.sh

@@ -3272,4 +3272,45 @@ EOF
   true
 }
 
+function test_legacy_label_print() {
+    WRKDIR=$(mktemp -d "${TEST_TMPDIR}/testXXXXXX")
+    cd "${WRKDIR}"
+    cat > WORKSPACE <<'EOF'
+load("//:my_repository_rule.bzl", "my_repository_rule")
+
+my_repository_rule(
+    name = "my_first_repo",
+)
+
+my_repository_rule(
+    name = "my_second_repo",
+)
+EOF
+    cat > my_repository_rule.bzl <<'EOF'
+def _my_repository_rule_impl(rctx):
+    print("main repo:", Label("@@//:foo"), str(Label("@@//:foo")))
+    print("my_first_repo:", Label("@my_first_repo//:foo"), str(Label("@my_first_repo//:foo")))
+    print("my_second_repo:", Label("@my_first_repo//:foo"), str(Label("@my_first_repo//:foo")))
+    rctx.file("WORKSPACE")
+    rctx.file("BUILD", "filegroup(name='foo',visibility=['//visibility:public'])")
+
+my_repository_rule = repository_rule(
+    implementation = _my_repository_rule_impl,
+)
+EOF
+    cat > BUILD <<'EOF'
+filegroup(
+    name = "foo",
+    srcs = [
+        "@my_first_repo//:foo",
+        "@my_second_repo//:foo",
+    ],
+)
+EOF
+    bazel build --noenable_bzlmod //:foo >& $TEST_log || fail "expected bazel to succeed"
+    expect_log "main repo: //:foo @//:foo"
+    expect_log "my_first_repo: @my_first_repo//:foo @my_first_repo//:foo"
+    expect_log "my_second_repo: @my_first_repo//:foo @my_first_repo//:foo"
+}
+
 run_suite "local repository tests"