Migrate annotations of SkylarkAttr to an interface class.

This isolates the API from the implementation.

RELNOTES: None.
PiperOrigin-RevId: 194850527

1 files changed, 960 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkAttrApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkAttrApi.java
new file mode 100644
index 0000000000..5c3c3a4292
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkAttrApi.java
@@ -0,0 +1,960 @@
+// Copyright 2018 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.skylarkbuildapi;
+
+import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.skylarkinterface.Param;
+import com.google.devtools.build.lib.skylarkinterface.ParamType;
+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.Environment;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.FuncallExpression;
+import com.google.devtools.build.lib.syntax.SkylarkDict;
+import com.google.devtools.build.lib.syntax.SkylarkList;
+import com.google.devtools.build.lib.syntax.UserDefinedFunction;
+
+/**
+ * The "attr" module of the Build API.
+ *
+ * <p>It exposes functions (for example, 'attr.string', 'attr.label_list', etc.) to Skylark users
+ * for creating attribute definitions.
+ */
+@SkylarkModule(
+    name = "attr",
+    namespace = true,
+    category = SkylarkModuleCategory.BUILTIN,
+    doc =
+        "Module for creating new attributes. "
+            + "They are only for use with <a href=\"globals.html#rule\">rule</a> or "
+            + "<a href=\"globals.html#aspect\">aspect</a>. "
+            + "<a href=\"https://github.com/bazelbuild/examples/tree/master/rules/"
+            + "attributes/printer.bzl\">See example of use</a>.")
+public interface SkylarkAttrApi extends SkylarkValue {
+
+  static final String ALLOW_FILES_ARG = "allow_files";
+  static final String ALLOW_FILES_DOC =
+      "Whether File targets are allowed. Can be True, False (default), or a list of file "
+          + "extensions that are allowed (for example, <code>[\".cc\", \".cpp\"]</code>).";
+
+  static final String ALLOW_RULES_ARG = "allow_rules";
+  static final String ALLOW_RULES_DOC =
+      "Which rule targets (name of the classes) are allowed. This is deprecated (kept only for "
+          + "compatibility), use providers instead.";
+
+  static final String ASPECTS_ARG = "aspects";
+  static final String ASPECTS_ARG_DOC =
+      "Aspects that should be applied to the dependency or dependencies specified by this "
+          + "attribute.";
+
+  static final String CONFIGURATION_ARG = "cfg";
+  static final String CONFIGURATION_DOC =
+      "<a href=\"../rules.$DOC_EXT#configurations\">Configuration</a> of the attribute. It can be "
+          + "either <code>\"data\"</code>, <code>\"host\"</code>, or <code>\"target\"</code>.";
+
+  static final String DEFAULT_ARG = "default";
+  // A trailing space is required because it's often prepended to other sentences
+  static final String DEFAULT_DOC = "The default value of the attribute. ";
+
+  static final String DOC_ARG = "doc";
+  static final String DOC_DOC =
+      "A description of the attribute that can be extracted by documentation generating tools.";
+
+  static final String EXECUTABLE_ARG = "executable";
+  static final String EXECUTABLE_DOC =
+      "True if the label has to be executable. This means the label must refer to an "
+          + "executable file, or to a rule that outputs an executable file. Access the label "
+          + "with <code>ctx.executable.&lt;attribute_name&gt;</code>.";
+
+  static final String FLAGS_ARG = "flags";
+  static final String FLAGS_DOC = "Deprecated, will be removed.";
+
+  static final String MANDATORY_ARG = "mandatory";
+  static final String MANDATORY_DOC = "True if the value must be explicitly specified.";
+
+  static final String NON_EMPTY_ARG = "non_empty";
+  static final String NON_EMPTY_DOC =
+      "True if the attribute must not be empty. Deprecated: Use allow_empty instead.";
+
+  static final String ALLOW_EMPTY_ARG = "allow_empty";
+  static final String ALLOW_EMPTY_DOC = "True if the attribute can be empty.";
+
+  static final String PROVIDERS_ARG = "providers";
+  static final String PROVIDERS_DOC =
+      "Mandatory providers list. It should be either a list of providers, or a "
+          + "list of lists of providers. Every dependency should provide ALL providers "
+          + "from at least ONE of these lists. A single list of providers will be "
+          + "automatically converted to a list containing one list of providers.";
+
+  static final String SINGLE_FILE_ARG = "single_file";
+  static final String ALLOW_SINGLE_FILE_ARG = "allow_single_file";
+
+  static final String VALUES_ARG = "values";
+  static final String VALUES_DOC =
+      "The list of allowed values for the attribute. An error is raised if any other "
+          + "value is given.";
+
+  @SkylarkCallable(
+      name = "int",
+      doc = "Creates an attribute of type int.",
+      parameters = {
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = Integer.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            defaultValue = "0",
+            doc = DEFAULT_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            doc = MANDATORY_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = VALUES_ARG,
+            type = SkylarkList.class,
+            generic1 = Integer.class,
+            defaultValue = "[]",
+            doc = VALUES_DOC,
+            named = true,
+            positional = false)
+      },
+      useAst = true,
+      useEnvironment = true)
+  Descriptor intAttribute(
+      Integer defaultInt,
+      String doc,
+      Boolean mandatory,
+      SkylarkList<?> values,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "string",
+      doc = "Creates an attribute of type <a href=\"string.html\">string</a>.",
+      parameters = {
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = String.class),
+            },
+            defaultValue = "''",
+            doc = DEFAULT_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            doc = MANDATORY_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = VALUES_ARG,
+            type = SkylarkList.class,
+            generic1 = String.class,
+            defaultValue = "[]",
+            doc = VALUES_DOC,
+            named = true,
+            positional = false)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor stringAttribute(
+      String defaultString,
+      String doc,
+      Boolean mandatory,
+      SkylarkList<?> values,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "label",
+      doc =
+          "Creates an attribute of type <a href=\"Target.html\">Target</a> which is the target "
+              + "referred to by the label. "
+              + "It is the only way to specify a dependency to another target. "
+              + "If you need a dependency that the user cannot overwrite, "
+              + "<a href=\"../rules.$DOC_EXT#private-attributes\">make the attribute private</a>.",
+      parameters = {
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = Label.class),
+              @ParamType(type = String.class),
+              @ParamType(type = LateBoundDefaultApi.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            callbackEnabled = true,
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            doc =
+                DEFAULT_DOC
+                    + "Use a string or the <a href=\"globals.html#Label\"><code>Label</code></a> "
+                    + "function to specify a default value, for example, "
+                    + "<code>attr.label(default = \"//a:b\")</code>."),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = EXECUTABLE_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = EXECUTABLE_DOC),
+        @Param(
+            name = ALLOW_FILES_ARG,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            noneable = true,
+            doc = ALLOW_FILES_DOC),
+        @Param(
+            name = ALLOW_SINGLE_FILE_ARG,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            noneable = true,
+            doc =
+                "This is similar to <code>allow_files</code>, with the restriction that the label "
+                    + "must correspond to a single <a href=\"File.html\">File</a>. "
+                    + "Access it through <code>ctx.file.&lt;attribute_name&gt;</code>."),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = MANDATORY_DOC),
+        @Param(
+            name = PROVIDERS_ARG,
+            type = SkylarkList.class,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = PROVIDERS_DOC),
+        @Param(
+            name = ALLOW_RULES_ARG,
+            type = SkylarkList.class,
+            generic1 = String.class,
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            doc = ALLOW_RULES_DOC),
+        @Param(
+            name = SINGLE_FILE_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc =
+                "Deprecated: Use <code>allow_single_file</code> instead. "
+                    + "If True, the label must correspond to a single "
+                    + "<a href=\"File.html\">File</a>. "
+                    + "Access it through <code>ctx.file.&lt;attribute_name&gt;</code>."),
+        @Param(
+            name = CONFIGURATION_ARG,
+            type = Object.class,
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            doc =
+                CONFIGURATION_DOC
+                    + " This parameter is required if <code>executable</code> is True."),
+        @Param(
+            name = ASPECTS_ARG,
+            type = SkylarkList.class,
+            generic1 = SkylarkAspectApi.class,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = ASPECTS_ARG_DOC),
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor labelAttribute(
+      Object defaultO,
+      String doc,
+      Boolean executable,
+      Object allowFiles,
+      Object allowSingleFile,
+      Boolean mandatory,
+      SkylarkList<?> providers,
+      Object allowRules,
+      Boolean singleFile,
+      Object cfg,
+      SkylarkList<?> aspects,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "string_list",
+      doc =
+          "Creates an attribute which is a <a href=\"list.html\">list</a> of "
+              + "<a href=\"string.html\">strings</a>.",
+      parameters = {
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            doc = MANDATORY_DOC,
+            named = true),
+        @Param(
+            name = NON_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            doc = NON_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = ALLOW_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "True",
+            doc = ALLOW_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = SkylarkList.class, generic1 = String.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            defaultValue = "[]",
+            doc = DEFAULT_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor stringListAttribute(
+      Boolean mandatory,
+      Boolean nonEmpty,
+      Boolean allowEmpty,
+      SkylarkList<?> defaultList,
+      String doc,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "int_list",
+      doc = "Creates an attribute which is a <a href=\"list.html\">list</a> of ints.",
+      parameters = {
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            doc = MANDATORY_DOC,
+            named = true),
+        @Param(
+            name = NON_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            doc = NON_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = ALLOW_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "True",
+            doc = ALLOW_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = SkylarkList.class, generic1 = Integer.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            defaultValue = "[]",
+            doc = DEFAULT_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor intListAttribute(
+      Boolean mandatory,
+      Boolean nonEmpty,
+      Boolean allowEmpty,
+      SkylarkList<?> defaultList,
+      String doc,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "label_list",
+      doc =
+          "Creates an attribute which is a <a href=\"list.html\">list</a> of type "
+              + "<a href=\"Target.html\">Target</a> which are specified by the labels in the list. "
+              + "See <a href=\"attr.html#label\">label</a> for more information.",
+      parameters = {
+        @Param(
+            name = ALLOW_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "True",
+            doc = ALLOW_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = SkylarkList.class, generic1 = Label.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            callbackEnabled = true,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc =
+                DEFAULT_DOC
+                    + "Use strings or the <a href=\"globals.html#Label\"><code>Label</code></a> "
+                    + "function to specify default values, for example, "
+                    + "<code>attr.label_list(default = [\"//a:b\", \"//a:c\"])</code>."),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = ALLOW_FILES_ARG, // bool or FileType filter
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            noneable = true,
+            doc = ALLOW_FILES_DOC),
+        @Param(
+            name = ALLOW_RULES_ARG,
+            type = SkylarkList.class,
+            generic1 = String.class,
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            doc = ALLOW_RULES_DOC),
+        @Param(
+            name = PROVIDERS_ARG,
+            type = SkylarkList.class,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = PROVIDERS_DOC),
+        @Param(
+            name = FLAGS_ARG,
+            type = SkylarkList.class,
+            generic1 = String.class,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = FLAGS_DOC),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = MANDATORY_DOC),
+        @Param(
+            name = NON_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = NON_EMPTY_DOC),
+        @Param(
+            name = CONFIGURATION_ARG,
+            type = Object.class,
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            doc = CONFIGURATION_DOC),
+        @Param(
+            name = ASPECTS_ARG,
+            type = SkylarkList.class,
+            generic1 = SkylarkAspectApi.class,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = ASPECTS_ARG_DOC),
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor labelListAttribute(
+      Boolean allowEmpty,
+      Object defaultList,
+      String doc,
+      Object allowFiles,
+      Object allowRules,
+      SkylarkList<?> providers,
+      SkylarkList<?> flags,
+      Boolean mandatory,
+      Boolean nonEmpty,
+      Object cfg,
+      SkylarkList<?> aspects,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "label_keyed_string_dict",
+      doc =
+          "Creates an attribute which is a <a href=\"dict.html\">dict</a>. Its keys are type "
+              + "<a href=\"Target.html\">Target</a> and are specified by the label keys of the "
+              + "input dict. Its values are <a href=\"string.html\">strings</a>. See "
+              + "<a href=\"attr.html#label\">label</a> for more information.",
+      parameters = {
+        @Param(
+            name = ALLOW_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "True",
+            doc = ALLOW_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = SkylarkDict.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            callbackEnabled = true,
+            defaultValue = "{}",
+            named = true,
+            positional = false,
+            doc =
+                DEFAULT_DOC
+                    + "Use strings or the <a href=\"globals.html#Label\"><code>Label</code></a> "
+                    + "function to specify default values, for example, "
+                    + "<code>attr.label_keyed_string_dict(default = "
+                    + "{\"//a:b\": \"value\", \"//a:c\": \"string\"})</code>."),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = ALLOW_FILES_ARG, // bool or FileType filter
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            noneable = true,
+            doc = ALLOW_FILES_DOC),
+        @Param(
+            name = ALLOW_RULES_ARG,
+            type = SkylarkList.class,
+            generic1 = String.class,
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            doc = ALLOW_RULES_DOC),
+        @Param(
+            name = PROVIDERS_ARG,
+            type = SkylarkList.class,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = PROVIDERS_DOC),
+        @Param(
+            name = FLAGS_ARG,
+            type = SkylarkList.class,
+            generic1 = String.class,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = FLAGS_DOC),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = MANDATORY_DOC),
+        @Param(
+            name = NON_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = NON_EMPTY_DOC),
+        @Param(
+            name = CONFIGURATION_ARG,
+            type = Object.class,
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            doc = CONFIGURATION_DOC),
+        @Param(
+            name = ASPECTS_ARG,
+            type = SkylarkList.class,
+            generic1 = SkylarkAspectApi.class,
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = ASPECTS_ARG_DOC)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor labelKeyedStringDictAttribute(
+      Boolean allowEmpty,
+      Object defaultList,
+      String doc,
+      Object allowFiles,
+      Object allowRules,
+      SkylarkList<?> providers,
+      SkylarkList<?> flags,
+      Boolean mandatory,
+      Boolean nonEmpty,
+      Object cfg,
+      SkylarkList<?> aspects,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "bool",
+      doc = "Creates an attribute of type bool.",
+      parameters = {
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = Boolean.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = DEFAULT_DOC),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = MANDATORY_DOC)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor boolAttribute(
+      Boolean defaultO, String doc, Boolean mandatory, FuncallExpression ast, Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "output",
+      doc =
+          "Creates an attribute of type output. "
+              + "The user provides a file name (string) and the rule must create an action that "
+              + "generates the file.",
+      parameters = {
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = Label.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            doc = DEFAULT_DOC),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = MANDATORY_DOC)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor outputAttribute(
+      Object defaultO, String doc, Boolean mandatory, FuncallExpression ast, Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "output_list",
+      doc =
+          "Creates an attribute which is a <a href=\"list.html\">list</a> of outputs. "
+              + "See <a href=\"attr.html#output\">output</a> for more information.",
+      parameters = {
+        @Param(
+            name = ALLOW_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "True",
+            doc = ALLOW_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = SkylarkList.class, generic1 = Label.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            defaultValue = "[]",
+            named = true,
+            positional = false,
+            doc = DEFAULT_DOC),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = MANDATORY_DOC),
+        @Param(
+            name = NON_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = NON_EMPTY_DOC)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor outputListAttribute(
+      Boolean allowEmpty,
+      SkylarkList defaultList,
+      String doc,
+      Boolean mandatory,
+      Boolean nonEmpty,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "string_dict",
+      doc =
+          "Creates an attribute of type <a href=\"dict.html\">dict</a>, mapping from "
+              + "<a href=\"string.html\">string</a> to <a href=\"string.html\">string</a>.",
+      parameters = {
+        @Param(
+            name = ALLOW_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "True",
+            doc = ALLOW_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = SkylarkDict.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            named = true,
+            positional = false,
+            defaultValue = "{}",
+            doc = DEFAULT_DOC),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            named = true,
+            positional = false,
+            defaultValue = "False",
+            doc = MANDATORY_DOC),
+        @Param(
+            name = NON_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = NON_EMPTY_DOC)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor stringDictAttribute(
+      Boolean allowEmpty,
+      SkylarkDict<?, ?> defaultO,
+      String doc,
+      Boolean mandatory,
+      Boolean nonEmpty,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "string_list_dict",
+      doc =
+          "Creates an attribute of type <a href=\"dict.html\">dict</a>, mapping from "
+              + "<a href=\"string.html\">string</a> to <a href=\"list.html\">list</a> of "
+              + "<a href=\"string.html\">string</a>.",
+      parameters = {
+        @Param(
+            name = ALLOW_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "True",
+            doc = ALLOW_EMPTY_DOC,
+            named = true),
+        @Param(
+            name = DEFAULT_ARG,
+            allowedTypes = {
+              @ParamType(type = SkylarkDict.class),
+              @ParamType(type = UserDefinedFunction.class)
+            },
+            defaultValue = "{}",
+            named = true,
+            positional = false,
+            doc = DEFAULT_DOC),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = MANDATORY_DOC),
+        @Param(
+            name = NON_EMPTY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = NON_EMPTY_DOC)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor stringListDictAttribute(
+      Boolean allowEmpty,
+      SkylarkDict<?, ?> defaultO,
+      String doc,
+      Boolean mandatory,
+      Boolean nonEmpty,
+      FuncallExpression ast,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+      name = "license",
+      doc = "Creates an attribute of type license.",
+      // TODO(bazel-team): Implement proper license support for Skylark.
+      parameters = {
+        // TODO(bazel-team): ensure this is the correct default value
+        @Param(
+            name = DEFAULT_ARG,
+            defaultValue = "None",
+            noneable = true,
+            named = true,
+            positional = false,
+            doc = DEFAULT_DOC),
+        @Param(
+            name = DOC_ARG,
+            type = String.class,
+            defaultValue = "''",
+            doc = DOC_DOC,
+            named = true,
+            positional = false),
+        @Param(
+            name = MANDATORY_ARG,
+            type = Boolean.class,
+            defaultValue = "False",
+            named = true,
+            positional = false,
+            doc = MANDATORY_DOC)
+      },
+      useAst = true,
+      useEnvironment = true)
+  public Descriptor licenseAttribute(
+      Object defaultO, String doc, Boolean mandatory, FuncallExpression ast, Environment env)
+      throws EvalException;
+
+  /** An attribute descriptor. */
+  @SkylarkModule(
+      name = "Attribute",
+      category = SkylarkModuleCategory.NONE,
+      doc =
+          "Representation of a definition of an attribute. Use the <a href=\"attr.html\">attr</a> "
+              + "module to create an Attribute. They are only for use with a "
+              + "<a href=\"globals.html#rule\">rule</a> or an "
+              + "<a href=\"globals.html#aspect\">aspect</a>.")
+  public static interface Descriptor extends SkylarkValue {}
+}