bazel syntax: make @Skylark-annotated classes implement SkylarkValue

This CL adds a check to the @SkylarkCallable annotation processor to require
that all SkylarkModule- or SkylarkGlobalLibary-annotated classes implement
SkylarkValue, thus ensuring that all Starlark values besides str/int/bool
satisfy this interface.

Future changes will add assertions at the public API (e.g. StarlarkList.add)
that Object values conform to this requirement.

All changes except to .../main/.../{skylarkinterface,syntax}/* are mechanical.

PiperOrigin-RevId: 278876512

src/main/java/com/google/devtools/build/docgen/SkylarkDocumentationCollector.java

@@ -25,6 +25,7 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkSignature;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.syntax.CallUtils;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
@@ -37,12 +38,11 @@
  */
 final class SkylarkDocumentationCollector {
   @SkylarkModule(
-    name = "globals",
-    title = "Globals",
-    category = SkylarkModuleCategory.TOP_LEVEL_TYPE,
-    doc = "Objects, functions and modules registered in the global environment."
-  )
-  private static final class TopLevelModule {}
+      name = "globals",
+      title = "Globals",
+      category = SkylarkModuleCategory.TOP_LEVEL_TYPE,
+      doc = "Objects, functions and modules registered in the global environment.")
+  private static final class TopLevelModule implements SkylarkValue {}
 
   private SkylarkDocumentationCollector() {}
 

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

@@ -1,13 +1,12 @@
 load("@rules_java//java:defs.bzl", "java_binary", "java_library")
+load(":merge_licenses.bzl", "merge_licenses")
 
 # Description:
 #   Main Java code for Bazel
 package(
     default_visibility = ["//src:__subpackages__"],
 )
 
-load(":merge_licenses.bzl", "merge_licenses")
-
 # Generate list of all srcs via:
 # bazel query 'filter("srcs", kind("filegroup rule", //src/main/java/com/google/devtools/build/lib/...))' | sort | sed -e "s/^/\"/" | sed -e "s/$/\",/" | fgrep -v "build/lib:srcs"
 filegroup(
@@ -399,6 +398,7 @@ java_library(
     ],
     deps = [
         ":skylark_semantics",
+        "//src/main/java/com/google/devtools/build/lib/concurrent",
         "//third_party:jsr305",
     ],
 )

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

@@ -34,7 +34,7 @@
 import java.util.Set;
 
 /** A global library of Starlark functions which are available only when evaluating BUILD files. */
-@SkylarkGlobalLibrary()
+@SkylarkGlobalLibrary
 class StarlarkBuildLibrary {
 
   /**

src/main/java/com/google/devtools/build/lib/rules/java/MessageBundleInfo.java

@@ -27,6 +27,7 @@
 import com.google.devtools.build.lib.skylarkinterface.Param;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.SkylarkList;
 import java.util.List;
@@ -35,7 +36,7 @@
 /** Marks configured targets that are able to supply message bundles to their dependents. */
 @AutoCodec
 @Immutable
-public final class MessageBundleInfo extends NativeInfo {
+public final class MessageBundleInfo extends NativeInfo implements SkylarkValue {
 
   public static final String SKYLARK_NAME = "MessageBundleInfo";
 

src/main/java/com/google/devtools/build/lib/rules/python/PythonConfiguration.java

@@ -23,6 +23,7 @@
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.util.OS;
 import com.google.devtools.common.options.TriState;
 
@@ -35,7 +36,7 @@
     name = "py",
     doc = "A configuration fragment for Python.",
     category = SkylarkModuleCategory.CONFIGURATION_FRAGMENT)
-public class PythonConfiguration extends BuildConfiguration.Fragment {
+public class PythonConfiguration extends BuildConfiguration.Fragment implements SkylarkValue {
 
   private final PythonVersion version;
   private final PythonVersion defaultVersion;

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/BuildConfigurationApi.java

@@ -18,16 +18,17 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
 /** Interface for a configuration object which holds information about the build environment. */
 @SkylarkModule(
     name = "configuration",
     category = SkylarkModuleCategory.BUILTIN,
-    doc = "This object holds information about the environment in which the build is running. See "
-        + "the <a href='../rules.$DOC_EXT#configurations'>Rules page</a> for more on the general "
-        + "concept of configurations."
-)
-public interface BuildConfigurationApi {
+    doc =
+        "This object holds information about the environment in which the build is running. See"
+            + " the <a href='../rules.$DOC_EXT#configurations'>Rules page</a> for more on the"
+            + " general concept of configurations.")
+public interface BuildConfigurationApi extends SkylarkValue {
 
   @SkylarkCallable(name = "bin_dir", structField = true, documented = false)
   @Deprecated

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/FileProviderApi.java

@@ -18,13 +18,14 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
 /** A representation of the concept "this builds these files". */
 @SkylarkModule(
     name = "file_provider",
     doc = "An interface for rules that provide files.",
     category = SkylarkModuleCategory.PROVIDER)
-public interface FileProviderApi {
+public interface FileProviderApi extends SkylarkValue {
 
   /**
    * Returns the set of files that are the "output" of this rule.

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/FilesToRunProviderApi.java

@@ -17,11 +17,12 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import javax.annotation.Nullable;
 
 /** Returns information about executables produced by a target and the files needed to run it. */
 @SkylarkModule(name = "FilesToRunProvider", doc = "", category = SkylarkModuleCategory.PROVIDER)
-public interface FilesToRunProviderApi<FileT extends FileApi> {
+public interface FilesToRunProviderApi<FileT extends FileApi> extends SkylarkValue {
 
   @SkylarkCallable(
     name = "executable",

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/FilesetEntryApi.java

@@ -15,13 +15,8 @@
 package com.google.devtools.build.lib.skylarkbuildapi;
 
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
-/**
- * A value object used to represent an entry inside a "Fileset" BUILD rule.
- */
-@SkylarkModule(
-    name = "FilesetEntry",
-    doc = "",
-    documented = false)
-public interface FilesetEntryApi {
-}
+/** A value object used to represent an entry inside a "Fileset" BUILD rule. */
+@SkylarkModule(name = "FilesetEntry", doc = "", documented = false)
+public interface FilesetEntryApi extends SkylarkValue {}

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/FragmentCollectionApi.java

@@ -16,6 +16,7 @@
 
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.syntax.ClassObject;
 
 /** Represents a collection of configuration fragments in Skylark. */
@@ -31,4 +32,4 @@
             + "ex:</p><code>ctx.fragments.apple</code></p>"
             + "Note that rules have to declare their required fragments in order to access them "
             + "(see <a href=\"../rules.md#fragments\">here</a>).")
-public interface FragmentCollectionApi extends ClassObject {}
+public interface FragmentCollectionApi extends ClassObject, SkylarkValue {}

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/ProtoConfigurationApi.java

@@ -16,14 +16,11 @@
 
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
-/**
- * A configuration fragment representing protocol buffers.
- */
+/** A configuration fragment representing protocol buffers. */
 @SkylarkModule(
     name = "proto",
     category = SkylarkModuleCategory.CONFIGURATION_FRAGMENT,
-    doc = "A configuration fragment representing protocol buffers."
-)
-public interface ProtoConfigurationApi {
-}
+    doc = "A configuration fragment representing protocol buffers.")
+public interface ProtoConfigurationApi extends SkylarkValue {}

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/RunfilesApi.java

@@ -19,13 +19,14 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
 /** An interface for a set of runfiles. */
 @SkylarkModule(
     name = "runfiles",
     category = SkylarkModuleCategory.BUILTIN,
     doc = "An interface for a set of runfiles.")
-public interface RunfilesApi {
+public interface RunfilesApi extends SkylarkValue {
 
   @SkylarkCallable(
     name = "files",

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkCommandLineApi.java

@@ -18,6 +18,7 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.skylarkinterface.StarlarkDeprecated;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
@@ -29,7 +30,7 @@
     category = SkylarkModuleCategory.TOP_LEVEL_TYPE,
     doc = "Deprecated. Module for creating memory efficient command lines.")
 @StarlarkDeprecated
-public interface SkylarkCommandLineApi {
+public interface SkylarkCommandLineApi extends SkylarkValue {
 
   @SkylarkCallable(
       name = "join_paths",

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkNativeModuleApi.java

@@ -19,15 +19,14 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.Runtime;
 import com.google.devtools.build.lib.syntax.SkylarkDict;
 import com.google.devtools.build.lib.syntax.SkylarkList;
 import com.google.devtools.build.lib.syntax.StarlarkThread;
 
-/**
- * Interface for a module with native rule and package helper functions.
- */
+/** Interface for a module with native rule and package helper functions. */
 @SkylarkModule(
     name = "native",
     category = SkylarkModuleCategory.BUILTIN,
@@ -38,9 +37,8 @@
             + "Note that the native module is only available in the loading phase "
             + "(i.e. for macros, not for rule implementations). Attributes will ignore "
             + "<code>None</code> values, and treat them as if the attribute was unset.<br>"
-            + "The following functions are also available:"
-)
-public interface SkylarkNativeModuleApi {
+            + "The following functions are also available:")
+public interface SkylarkNativeModuleApi extends SkylarkValue {
 
   @SkylarkCallable(
       name = "glob",

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/TargetApi.java

@@ -17,12 +17,11 @@
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
-/**
- * A node in the build dependency graph, identified by a Label.
- */
+/** A node in the build dependency graph, identified by a Label. */
 @SkylarkModule(name = "target", doc = "", documented = false)
-public interface TargetApi {
+public interface TargetApi extends SkylarkValue {
 
   /**
    * Returns the label of this target.  (e.g. "//foo:bar")

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/TransitiveInfoCollectionApi.java

@@ -18,36 +18,29 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
 import com.google.devtools.build.lib.syntax.StarlarkSemantics.FlagIdentifier;
 
-/**
- * Interface for a build target.
- */
+/** Interface for a build target. */
 @SkylarkModule(
-  name = "Target",
-  category = SkylarkModuleCategory.BUILTIN,
-  doc =
-      "A BUILD target. It is essentially a <code>struct</code> with the following fields:"
-          + "<ul>"
-          + "<li><h3 id=\"modules.Target.label\">label</h3><code><a class=\"anchor\" "
-          + "href=\"Label.html\">Label</a> Target.label</code><br>The identifier of the "
-          + "target.</li>"
-          + "<li><h3 id=\"modules.Target.files\">files</h3><code><a class=\"anchor\" "
-          + "href=\"depset.html\">depset</a> Target.files </code><br>The set of "
-          + "<a class=\"anchor\" href=\"File.html\">File</a>s produced directly by this "
-          + "target.</li>"
-          + "<li><h3 id=\"modules.Target.aspect_ids\">aspect_ids</h3><code><a class=\"anchor\""
-          + "href=\"list.html\">list</a> Target.aspect_ids </code><br>The list of "
-          + "<a class=\"anchor\" href=\"ctx.html#aspect_id\">aspect_id</a>s applied to this "
-          + "target.</li>"
-          + "<li><h3 id=\"modules.Target.extraproviders\">Extra providers</h3>For rule targets all "
-          + "additional providers provided by this target are accessible as <code>struct</code> "
-          + "fields. These extra providers are defined in the <code>struct</code> returned by the "
-          + "rule implementation function.</li>"
-          + "</ul>"
-)
-public interface TransitiveInfoCollectionApi {
+    name = "Target",
+    category = SkylarkModuleCategory.BUILTIN,
+    doc =
+        "A BUILD target. It is essentially a <code>struct</code> with the following fields:"
+            + "<ul><li><h3 id=\"modules.Target.label\">label</h3><code><a class=\"anchor\""
+            + " href=\"Label.html\">Label</a> Target.label</code><br>The identifier of the "
+            + "target.</li><li><h3 id=\"modules.Target.files\">files</h3><code><a class=\"anchor\""
+            + " href=\"depset.html\">depset</a> Target.files </code><br>The set of <a"
+            + " class=\"anchor\" href=\"File.html\">File</a>s produced directly by this "
+            + "target.</li><li><h3 id=\"modules.Target.aspect_ids\">aspect_ids</h3><code><a"
+            + " class=\"anchor\"href=\"list.html\">list</a> Target.aspect_ids </code><br>The list"
+            + " of <a class=\"anchor\" href=\"ctx.html#aspect_id\">aspect_id</a>s applied to this "
+            + "target.</li><li><h3 id=\"modules.Target.extraproviders\">Extra providers</h3>For"
+            + " rule targets all additional providers provided by this target are accessible as"
+            + " <code>struct</code> fields. These extra providers are defined in the"
+            + " <code>struct</code> returned by the rule implementation function.</li></ul>")
+public interface TransitiveInfoCollectionApi extends SkylarkValue {
 
   @SkylarkCallable(
     name = "output_group",

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/android/AndroidBinaryDataSettingsApi.java

@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.skylarkbuildapi.android;
 
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
 /** Wraps common settings for working with android binary assets, resources, and manifests. */
 @SkylarkModule(
@@ -24,4 +25,4 @@
             + "Wraps common settings for working with android binary assets, resources, and "
             + "manifest",
     documented = false)
-public interface AndroidBinaryDataSettingsApi {}
+public interface AndroidBinaryDataSettingsApi extends SkylarkValue {}

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/android/AndroidConfigurationApi.java

@@ -17,6 +17,7 @@
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
 /** Configuration fragment for Android rules. */
 @SkylarkModule(
@@ -27,7 +28,7 @@
             + "A configuration fragment for Android.",
     documented = false,
     category = SkylarkModuleCategory.CONFIGURATION_FRAGMENT)
-public interface AndroidConfigurationApi {
+public interface AndroidConfigurationApi extends SkylarkValue {
 
   @SkylarkCallable(
       name = "android_cpu",

src/main/java/com/google/devtools/build/lib/skylarkbuildapi/android/AndroidDataContextApi.java

@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.skylarkbuildapi.android;
 
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
 /**
  * Wraps common tools and settings used for working with Android assets, resources, and manifests.
@@ -26,4 +27,4 @@
             + "Wraps common tools and settings used for working with Android assets, resources, and"
             + " manifests",
     documented = false)
-public interface AndroidDataContextApi {}
+public interface AndroidDataContextApi extends SkylarkValue {}