Allow modules to specify their own repo names

With the `repo_name` attribute in the `module` directive, a module can specify its own repo name for itself and any extensions it contains. This is particularly useful during migration.

PiperOrigin-RevId: 472299124
Change-Id: I0febecfcfe73343e8bd52ce13e5dbb22581858e4

src/main/java/com/google/devtools/build/lib/bazel/bzlmod/Module.java

@@ -23,6 +23,7 @@
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Map;
+import java.util.Optional;
 import java.util.function.UnaryOperator;
 import javax.annotation.Nullable;
 
@@ -74,6 +75,13 @@ public final RepositoryName getCanonicalRepoName() {
    */
   public abstract int getCompatibilityLevel();
 
+  /**
+   * The name of the repository representing this module, as seen by the module itself. By default,
+   * the name of the repo is the name of the module. This can be specified to ease migration for
+   * projects that have been using a repo name for itself that differs from its module name.
+   */
+  public abstract String getRepoName();
+
   /**
    * Target patterns identifying execution platforms to register when this module is selected. Note
    * that these are what was written in module files verbatim, and don't contain canonical repo
@@ -112,10 +120,10 @@ public final RepositoryMapping getRepoMappingWithBazelDepsOnly() {
     if (getKey().equals(ModuleKey.ROOT)) {
       mapping.put("", RepositoryName.MAIN);
     }
-    // Every module should be able to reference itself as @<module name>.
-    // If this is the root module, this perfectly falls into @<module name> => @
-    if (!getName().isEmpty()) {
-      mapping.put(getName(), getCanonicalRepoName());
+    // Every module should be able to reference itself as @<module repo name>.
+    // If this is the root module, this perfectly falls into @<module repo name> => @
+    if (!getRepoName().isEmpty()) {
+      mapping.put(getRepoName(), getCanonicalRepoName());
     }
     for (Map.Entry<String, ModuleKey> dep : getDeps().entrySet()) {
       // Special note: if `dep` is actually the root module, its ModuleKey would be ROOT whose
@@ -172,6 +180,9 @@ public abstract static class Builder {
     /** Optional; defaults to {@code 0}. */
     public abstract Builder setCompatibilityLevel(int value);
 
+    /** Optional; defaults to {@link #setName}. */
+    public abstract Builder setRepoName(String value);
+
     abstract ImmutableList.Builder<String> executionPlatformsToRegisterBuilder();
 
     @CanIgnoreReturnValue
@@ -220,6 +231,17 @@ public Builder addExtensionUsage(ModuleExtensionUsage value) {
       return this;
     }
 
-    abstract Module build();
+    abstract String getName();
+
+    abstract Optional<String> getRepoName();
+
+    abstract Module autoBuild();
+
+    final Module build() {
+      if (getRepoName().isEmpty()) {
+        setRepoName(getName());
+      }
+      return autoBuild();
+    }
   }
 }

src/main/java/com/google/devtools/build/lib/bazel/bzlmod/ModuleFileGlobals.java

@@ -157,6 +157,16 @@ static void validateModuleName(String moduleName) throws EvalException {
             named = true,
             positional = false,
             defaultValue = "0"),
+        @Param(
+            name = "repo_name",
+            doc =
+                "The name of the repository representing this module, as seen by the module itself."
+                    + " By default, the name of the repo is the name of the module. This can be"
+                    + " specified to ease migration for projects that have been using a repo name"
+                    + " for itself that differs from its module name.",
+            named = true,
+            positional = false,
+            defaultValue = "''"),
         @Param(
             name = "execution_platforms_to_register",
             doc =
@@ -187,6 +197,7 @@ public void module(
       String name,
       String version,
       StarlarkInt compatibilityLevel,
+      String repoName,
       Iterable<?> executionPlatformsToRegister,
       Iterable<?> toolchainsToRegister,
       StarlarkThread thread)
@@ -198,6 +209,13 @@ public void module(
     if (!name.isEmpty()) {
       validateModuleName(name);
     }
+    if (repoName.isEmpty()) {
+      repoName = name;
+      addRepoNameUsage(name, "as the current module name", thread.getCallerLocation());
+    } else {
+      RepositoryName.validateUserProvidedRepoName(repoName);
+      addRepoNameUsage(repoName, "as the module's own repo name", thread.getCallerLocation());
+    }
     Version parsedVersion;
     try {
       parsedVersion = Version.parse(version);
@@ -210,12 +228,12 @@ public void module(
         .setName(name)
         .setVersion(parsedVersion)
         .setCompatibilityLevel(compatibilityLevel.toInt("compatibility_level"))
+        .setRepoName(repoName)
         .addExecutionPlatformsToRegister(
             checkAllAbsolutePatterns(
                 executionPlatformsToRegister, "execution_platforms_to_register"))
         .addToolchainsToRegister(
             checkAllAbsolutePatterns(toolchainsToRegister, "toolchains_to_register"));
-    addRepoNameUsage(name, "as the current module name", thread.getCallerLocation());
   }
 
   private static ImmutableList<String> checkAllAbsolutePatterns(Iterable<?> iterable, String where)

src/test/java/com/google/devtools/build/lib/bazel/bzlmod/BzlmodTestUtil.java

@@ -95,6 +95,12 @@ public ModuleBuilder setKey(ModuleKey value) {
       return this;
     }
 
+    @CanIgnoreReturnValue
+    public ModuleBuilder setRepoName(String value) {
+      this.builder.setRepoName(value);
+      return this;
+    }
+
     @CanIgnoreReturnValue
     public ModuleBuilder setRegistry(FakeRegistry value) {
       this.builder.setRegistry(value);

src/test/java/com/google/devtools/build/lib/bazel/bzlmod/ModuleExtensionResolutionTest.java

@@ -894,8 +894,7 @@ public void generatedReposHaveCorrectMappings() throws Exception {
         "def _ext_impl(ctx):",
         "  internal_repo(name='internal')",
         "  ext_repo(name='ext')",
-        "tag=tag_class(attrs={'file':attr.label()})",
-        "ext=module_extension(implementation=_ext_impl,tag_classes={'tag':tag})");
+        "ext=module_extension(implementation=_ext_impl)");
 
     registry.addModule(createModuleKey("foo", "1.0"), "module(name='foo',version='1.0')");
     scratch.file(modulesRoot.getRelative("foo~1.0/WORKSPACE").getPathString());
@@ -912,6 +911,42 @@ public void generatedReposHaveCorrectMappings() throws Exception {
         .isEqualTo("foo: foo-stuff internal: internal-stuff");
   }
 
+  @Test
+  public void generatedReposHaveCorrectMappings_moduleOwnRepoName() throws Exception {
+    // tests that things work correctly when the module specifies its own repo name (via
+    // `module(repo_name=...)`).
+    scratch.file(
+        workspaceRoot.getRelative("MODULE.bazel").getPathString(),
+        "module(name='foo',version='1.0',repo_name='bar')",
+        "ext = use_extension('//:defs.bzl','ext')",
+        "use_repo(ext,'ext')");
+    scratch.file(workspaceRoot.getRelative("BUILD").getPathString());
+    scratch.file(workspaceRoot.getRelative("data.bzl").getPathString(), "data='hello world'");
+    scratch.file(
+        workspaceRoot.getRelative("defs.bzl").getPathString(),
+        "def _ext_repo_impl(ctx):",
+        "  ctx.file('WORKSPACE')",
+        "  ctx.file('BUILD')",
+        "  ctx.file('data.bzl', \"\"\"load('@bar//:data.bzl', bar_data='data')",
+        "data = 'bar: '+bar_data",
+        "\"\"\")",
+        "ext_repo = repository_rule(implementation=_ext_repo_impl)",
+        "",
+        "ext=module_extension(implementation=lambda ctx: ext_repo(name='ext'))");
+    scratch.file(
+        workspaceRoot.getRelative("ext_data.bzl").getPathString(),
+        "load('@ext//:data.bzl', ext_data='data')",
+        "data='ext: ' + ext_data");
+
+    SkyKey skyKey = BzlLoadValue.keyForBuild(Label.parseCanonical("//:ext_data.bzl"));
+    EvaluationResult<BzlLoadValue> result =
+        evaluator.evaluate(ImmutableList.of(skyKey), evaluationContext);
+    if (result.hasError()) {
+      throw result.getError().getException();
+    }
+    assertThat(result.get(skyKey).getModule().getGlobal("data")).isEqualTo("ext: bar: hello world");
+  }
+
   @Test
   public void generatedReposHaveCorrectMappings_internalRepoWins() throws Exception {
     scratch.file(

src/test/java/com/google/devtools/build/lib/bazel/bzlmod/ModuleFileFunctionTest.java

@@ -729,6 +729,18 @@ public void badModuleName_bazelDep() throws Exception {
     assertContainsEvent("invalid module name 'f.'");
   }
 
+  @Test
+  public void badRepoName_module() throws Exception {
+    scratch.file(
+        rootDirectory.getRelative("MODULE.bazel").getPathString(),
+        "module(name='foo',version='0.1',repo_name='_foo')");
+
+    reporter.removeHandler(failFastHandler); // expect failures
+    evaluator.evaluate(ImmutableList.of(ModuleFileValue.KEY_FOR_ROOT_MODULE), evaluationContext);
+
+    assertContainsEvent("invalid user-provided repo name '_foo'");
+  }
+
   @Test
   public void badRepoName_bazelDep() throws Exception {
     scratch.file(
@@ -833,4 +845,39 @@ public void testBuiltinModules_forBuiltinModules() throws Exception {
                 .addDep("foo", createModuleKey("foo", "2.0"))
                 .build());
   }
+
+  @Test
+  public void moduleRepoName() throws Exception {
+    scratch.file(
+        rootDirectory.getRelative("MODULE.bazel").getPathString(),
+        "module(name='aaa',version='0.1',repo_name='bbb')");
+    FakeRegistry registry = registryFactory.newFakeRegistry("/foo");
+    ModuleFileFunction.REGISTRIES.set(differencer, ImmutableList.of(registry.getUrl()));
+
+    EvaluationResult<RootModuleFileValue> result =
+        evaluator.evaluate(
+            ImmutableList.of(ModuleFileValue.KEY_FOR_ROOT_MODULE), evaluationContext);
+    if (result.hasError()) {
+      fail(result.getError().toString());
+    }
+    RootModuleFileValue rootModuleFileValue = result.get(ModuleFileValue.KEY_FOR_ROOT_MODULE);
+    assertThat(rootModuleFileValue.getModule())
+        .isEqualTo(
+            ModuleBuilder.create("aaa", "0.1").setKey(ModuleKey.ROOT).setRepoName("bbb").build());
+  }
+
+  @Test
+  public void moduleRepoName_conflict() throws Exception {
+    scratch.file(
+        rootDirectory.getRelative("MODULE.bazel").getPathString(),
+        "module(name='aaa',version='0.1',repo_name='bbb')",
+        "bazel_dep(name='bbb',version='1.0')");
+    FakeRegistry registry = registryFactory.newFakeRegistry("/foo");
+    ModuleFileFunction.REGISTRIES.set(differencer, ImmutableList.of(registry.getUrl()));
+
+    reporter.removeHandler(failFastHandler); // expect failures
+    evaluator.evaluate(ImmutableList.of(ModuleFileValue.KEY_FOR_ROOT_MODULE), evaluationContext);
+
+    assertContainsEvent("The repo name 'bbb' is already being used as the module's own repo name");
+  }
 }

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

@@ -145,7 +145,7 @@ public void testSimpleMapping() throws Exception {
   }
 
   @Test
-  public void testRepoNameMapping_asMainModule() throws Exception {
+  public void testRepoNameMapping_asRootModule() throws Exception {
     scratch.overwriteFile(
         "MODULE.bazel",
         "module(name='aaa',version='0.1')",
@@ -173,6 +173,35 @@ public void testRepoNameMapping_asMainModule() throws Exception {
                 name));
   }
 
+  @Test
+  public void testRepoNameMapping_asRootModule_withOwnRepoName() throws Exception {
+    scratch.overwriteFile(
+        "MODULE.bazel",
+        "module(name='aaa',version='0.1',repo_name='haha')",
+        "bazel_dep(name='bbb',version='1.0', repo_name = 'com_foo_bar_b')");
+    registry.addModule(createModuleKey("bbb", "1.0"), "module(name='bbb', version='1.0')");
+
+    RepositoryName name = RepositoryName.MAIN;
+    SkyKey skyKey = RepositoryMappingValue.key(name);
+    EvaluationResult<RepositoryMappingValue> result = eval(skyKey);
+
+    assertThat(result.hasError()).isFalse();
+    assertThatEvaluationResult(result)
+        .hasEntryThat(skyKey)
+        .isEqualTo(
+            withMappingForRootModule(
+                ImmutableMap.of(
+                    "",
+                    RepositoryName.MAIN,
+                    "haha",
+                    RepositoryName.MAIN,
+                    TestConstants.WORKSPACE_NAME,
+                    RepositoryName.MAIN,
+                    "com_foo_bar_b",
+                    RepositoryName.create("bbb~1.0")),
+                name));
+  }
+
   @Test
   public void testRepoNameMapping_asDependency() throws Exception {
     scratch.overwriteFile(