Implement REPO.bazel

- REPO.bazel is a new file at the root of repos that can only contain a `repo()` call with a bunch of package default arguments (similar to `package()`)
- A new SkyFunction, RepoFileFunction, evaluates a REPO.bazel file and returns the `PackageArgs` object containing those arguments
- PackageFunction for packages in repo `@foo` now depends on RepoFileFunction for `@foo`

Fixes #18077

PiperOrigin-RevId: 551313372
Change-Id: If5769edec49fef148d17596f524ab7df935862b4

src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkGlobalsImpl.java

@@ -22,6 +22,7 @@
 import com.google.devtools.build.lib.collect.nestedset.Depset;
 import com.google.devtools.build.lib.packages.BuildGlobals;
 import com.google.devtools.build.lib.packages.Proto;
+import com.google.devtools.build.lib.packages.RepoCallable;
 import com.google.devtools.build.lib.packages.SelectorList;
 import com.google.devtools.build.lib.packages.StarlarkGlobals;
 import com.google.devtools.build.lib.packages.StarlarkNativeModule;
@@ -120,4 +121,11 @@ public ImmutableMap<String, Object> getSclToplevels() {
     env.put("struct", StructProvider.STRUCT);
     return env.buildOrThrow();
   }
+
+  @Override
+  public ImmutableMap<String, Object> getRepoToplevels() {
+    ImmutableMap.Builder<String, Object> env = ImmutableMap.builder();
+    Starlark.addMethods(env, RepoCallable.INSTANCE);
+    return env.buildOrThrow();
+  }
 }

src/main/java/com/google/devtools/build/lib/cmdline/LabelConstants.java

@@ -44,6 +44,7 @@ public class LabelConstants {
   public static final PathFragment WORKSPACE_DOT_BAZEL_FILE_NAME =
       PathFragment.create("WORKSPACE.bazel");
   public static final PathFragment MODULE_DOT_BAZEL_FILE_NAME = PathFragment.create("MODULE.bazel");
+  public static final PathFragment REPO_FILE_NAME = PathFragment.create("REPO.bazel");
 
   public static final PathFragment MODULE_LOCKFILE_NAME = PathFragment.create("MODULE.bazel.lock");
 

src/main/java/com/google/devtools/build/lib/packages/PackageArgs.java

@@ -37,6 +37,8 @@
  */
 @AutoValue
 public abstract class PackageArgs {
+  public static final PackageArgs EMPTY = PackageArgs.builder().build();
+
   public static final PackageArgs DEFAULT =
       PackageArgs.builder()
           .setDefaultVisibility(RuleVisibility.PRIVATE)

src/main/java/com/google/devtools/build/lib/packages/RepoCallable.java

@@ -0,0 +1,59 @@
+// Copyright 2023 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.packages;
+
+import java.util.Map;
+import net.starlark.java.annot.Param;
+import net.starlark.java.annot.StarlarkMethod;
+import net.starlark.java.eval.EvalException;
+import net.starlark.java.eval.Starlark;
+import net.starlark.java.eval.StarlarkThread;
+
+/** Definition of the {@code repo()} function used in REPO.bazel files. */
+public final class RepoCallable {
+  private RepoCallable() {}
+
+  public static final RepoCallable INSTANCE = new RepoCallable();
+
+  @StarlarkMethod(
+      name = "repo",
+      documented = false, // documented separately
+      extraKeywords = @Param(name = "kwargs"),
+      useStarlarkThread = true)
+  public Object repoCallable(Map<String, Object> kwargs, StarlarkThread thread)
+      throws EvalException {
+    RepoThreadContext context = RepoThreadContext.fromOrFail(thread, "repo()");
+    if (context.isRepoFunctionCalled()) {
+      throw Starlark.errorf("'repo' can only be called once in the REPO.bazel file");
+    }
+    context.setRepoFunctionCalled();
+
+    if (kwargs.isEmpty()) {
+      throw Starlark.errorf("at least one argument must be given to the 'repo' function");
+    }
+
+    PackageArgs.Builder pkgArgsBuilder = PackageArgs.builder();
+    for (Map.Entry<String, Object> kwarg : kwargs.entrySet()) {
+      PackageArgs.processParam(
+          kwarg.getKey(),
+          kwarg.getValue(),
+          "repo() argument '" + kwarg.getKey() + "'",
+          context.getLabelConverter(),
+          pkgArgsBuilder);
+    }
+    context.setPackageArgs(pkgArgsBuilder.build());
+    return Starlark.NONE;
+  }
+}

src/main/java/com/google/devtools/build/lib/packages/RepoThreadContext.java

@@ -0,0 +1,63 @@
+// Copyright 2023 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.packages;
+
+import net.starlark.java.eval.EvalException;
+import net.starlark.java.eval.Starlark;
+import net.starlark.java.eval.StarlarkThread;
+
+/** Context object for a Starlark thread evaluating the REPO.bazel file. */
+public class RepoThreadContext {
+  private final LabelConverter labelConverter;
+  private PackageArgs packageArgs = PackageArgs.EMPTY;
+  private boolean repoFunctionCalled = false;
+
+  public static RepoThreadContext fromOrFail(StarlarkThread thread, String what)
+      throws EvalException {
+    RepoThreadContext context = thread.getThreadLocal(RepoThreadContext.class);
+    if (context == null) {
+      throw Starlark.errorf("%s can only be called from REPO.bazel", what);
+    }
+    return context;
+  }
+
+  public void storeInThread(StarlarkThread thread) {
+    thread.setThreadLocal(RepoThreadContext.class, this);
+  }
+
+  public RepoThreadContext(LabelConverter labelConverter) {
+    this.labelConverter = labelConverter;
+  }
+
+  public LabelConverter getLabelConverter() {
+    return labelConverter;
+  }
+
+  public boolean isRepoFunctionCalled() {
+    return repoFunctionCalled;
+  }
+
+  public void setRepoFunctionCalled() {
+    repoFunctionCalled = true;
+  }
+
+  public void setPackageArgs(PackageArgs packageArgs) {
+    this.packageArgs = packageArgs;
+  }
+
+  public PackageArgs getPackageArgs() {
+    return packageArgs;
+  }
+}

src/main/java/com/google/devtools/build/lib/packages/StarlarkGlobals.java

@@ -64,4 +64,7 @@ public interface StarlarkGlobals {
 
   /** Returns the top-levels for .scl files. */
   ImmutableMap<String, Object> getSclToplevels();
+
+  /** Returns the top-levels for REPO.bazel files. */
+  ImmutableMap<String, Object> getRepoToplevels();
 }

src/main/java/com/google/devtools/build/lib/packages/StarlarkNativeModule.java

@@ -68,7 +68,6 @@
 import net.starlark.java.syntax.Location;
 
 /** The Starlark native module. */
-// TODO(cparsons): Move the definition of native.package() to this class.
 public class StarlarkNativeModule implements StarlarkNativeModuleApi {
   private static final GoogleLogger logger = GoogleLogger.forEnclosingClass();
 

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

@@ -167,6 +167,8 @@ java_library(
         ":recursive_package_provider_backed_target_pattern_resolver",
         ":recursive_pkg_function",
         ":recursive_pkg_value",
+        ":repo_file_function",
+        ":repo_file_value",
         ":repository_mapping_function",
         ":repository_mapping_value",
         ":rule_configured_target_value",
@@ -2194,6 +2196,40 @@ java_library(
     ],
 )
 
+java_library(
+    name = "repo_file_function",
+    srcs = ["RepoFileFunction.java"],
+    deps = [
+        ":precomputed_value",
+        ":repo_file_value",
+        ":repository_mapping_value",
+        "//src/main/java/com/google/devtools/build/lib/actions:file_metadata",
+        "//src/main/java/com/google/devtools/build/lib/cmdline",
+        "//src/main/java/com/google/devtools/build/lib/events",
+        "//src/main/java/com/google/devtools/build/lib/packages",
+        "//src/main/java/com/google/devtools/build/lib/rules:repository/repository_directory_value",
+        "//src/main/java/com/google/devtools/build/lib/vfs",
+        "//src/main/java/com/google/devtools/build/lib/vfs:pathfragment",
+        "//src/main/java/com/google/devtools/build/skyframe",
+        "//src/main/java/com/google/devtools/build/skyframe:skyframe-objects",
+        "//src/main/java/net/starlark/java/eval",
+        "//src/main/java/net/starlark/java/syntax",
+        "//third_party:jsr305",
+    ],
+)
+
+java_library(
+    name = "repo_file_value",
+    srcs = ["RepoFileValue.java"],
+    deps = [
+        ":sky_functions",
+        "//src/main/java/com/google/devtools/build/lib/cmdline",
+        "//src/main/java/com/google/devtools/build/lib/packages",
+        "//src/main/java/com/google/devtools/build/skyframe:skyframe-objects",
+        "//third_party:auto_value",
+    ],
+)
+
 java_library(
     name = "repository_mapping_function",
     srcs = ["RepositoryMappingFunction.java"],

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

@@ -63,6 +63,7 @@
 import com.google.devtools.build.lib.server.FailureDetails.PackageLoading.Code;
 import com.google.devtools.build.lib.skyframe.BzlLoadFunction.BzlLoadFailedException;
 import com.google.devtools.build.lib.skyframe.GlobValue.InvalidGlobPatternException;
+import com.google.devtools.build.lib.skyframe.RepoFileFunction.BadRepoFileException;
 import com.google.devtools.build.lib.skyframe.StarlarkBuiltinsFunction.BuiltinsFailedException;
 import com.google.devtools.build.lib.util.DetailedExitCode;
 import com.google.devtools.build.lib.util.Pair;
@@ -1240,6 +1241,24 @@ private LoadedPackage loadPackage(
     IgnoredPackagePrefixesValue repositoryIgnoredPackagePrefixes =
         (IgnoredPackagePrefixesValue)
             env.getValue(IgnoredPackagePrefixesValue.key(packageId.getRepository()));
+    RepoFileValue repoFileValue;
+    try {
+      repoFileValue =
+          (RepoFileValue)
+              env.getValueOrThrow(
+                  RepoFileValue.key(packageId.getRepository()),
+                  IOException.class,
+                  BadRepoFileException.class);
+    } catch (IOException | BadRepoFileException e) {
+      throw PackageFunctionException.builder()
+          .setType(PackageFunctionException.Type.BUILD_FILE_CONTAINS_ERRORS)
+          .setPackageIdentifier(packageId)
+          .setTransience(Transience.PERSISTENT)
+          .setException(e)
+          .setMessage("bad REPO.bazel file")
+          .setPackageLoadingCode(PackageLoading.Code.BAD_REPO_FILE)
+          .build();
+    }
     if (env.valuesMissing()) {
       return null;
     }
@@ -1375,8 +1394,9 @@ private LoadedPackage loadPackage(
               .setFilename(buildFileRootedPath)
               .setConfigSettingVisibilityPolicy(configSettingVisibilityPolicy);
 
-      pkgBuilder.mergePackageArgsFrom(
-          PackageArgs.builder().setDefaultVisibility(defaultVisibility));
+      pkgBuilder
+          .mergePackageArgsFrom(PackageArgs.builder().setDefaultVisibility(defaultVisibility))
+          .mergePackageArgsFrom(repoFileValue.packageArgs());
 
       Set<SkyKey> globDepKeys = ImmutableSet.of();