Expose AppleConfiguration to skylark as fragment "apple", along with …

…a callable method apple_host_system_env to return environment variables needed for various commands on apple hosts.

--
MOS_MIGRATED_REVID=114550659

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

@@ -461,23 +461,21 @@ public Label getLabel() {
   }
 
   @SkylarkCallable(name = "fragments", structField = true,
-      doc =
-      "Allows access to configuration fragments in target configuration. "
-      + "Possible fields are <code>cpp</code>, "
-      + "<code>java</code> and <code>jvm</code>. "
-      + "However, rules have to declare their required fragments in order to access them "
-      + "(see <a href=\"../rules.html#fragments\">here</a>).")
+      doc = "Allows access to configuration fragments in target configuration. "
+          + "Possible fields are <code>apple</code>, <code>cpp</code>, "
+          + "<code>java</code> and <code>jvm</code>. "
+          + "However, rules have to declare their required fragments in order to access them "
+          + "(see <a href=\"../rules.html#fragments\">here</a>).")
   public FragmentCollection getFragments() {
     return fragments;
   }
 
   @SkylarkCallable(name = "host_fragments", structField = true,
-      doc =
-      "Allows access to configuration fragments in host configuration. "
-      + "Possible fields are <code>cpp</code>, "
-      + "<code>java</code> and <code>jvm</code>. "
-      + "However, rules have to declare their required fragments in order to access them "
-      + "(see <a href=\"../rules.html#fragments\">here</a>).")
+      doc = "Allows access to configuration fragments in host configuration. "
+          + "Possible fields are <code>apple</code>, <code>cpp</code>, "
+          + "<code>java</code> and <code>jvm</code>. "
+          + "However, rules have to declare their required fragments in order to access them "
+          + "(see <a href=\"../rules.html#fragments\">here</a>).")
   public FragmentCollection getHostFragments() {
     return hostFragments;
   }

src/main/java/com/google/devtools/build/lib/rules/apple/AppleConfiguration.java

@@ -27,6 +27,8 @@
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions.AppleBitcodeMode;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.util.Preconditions;
 
 import java.util.Map;
@@ -36,6 +38,7 @@
 /**
  * A configuration containing flags required for Apple platforms and tools.
  */
+@SkylarkModule(name = "apple", doc = "A configuration fragment for Apple platforms")
 @Immutable
 public class AppleConfiguration extends BuildConfiguration.Fragment {
   public static final String XCODE_VERSION_ENV_NAME = "XCODE_VERSION_OVERRIDE";
@@ -107,6 +110,13 @@ public Map<String, String> getEnvironmentForIosAction() {
    * apple host system. These environment variables are needed by the apple toolchain. Keys are
    * variable names and values are their corresponding values.
    */
+  @SkylarkCallable(
+      name = "apple_host_system_env",
+      doc =
+          "Returns a map of environment variables that should be propagated for actions that "
+          + "build on an apple host system. These environment variables are needed by the apple "
+          + "toolchain. Keys are variable names and values are their corresponding values."
+    )
   public Map<String, String> getAppleHostSystemEnv() {
     Optional<DottedVersion> xcodeVersion = getXcodeVersion();
     ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();

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

@@ -17,6 +17,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib:packages-internal",
         "//src/main/java/com/google/devtools/build/lib:preconditions",
         "//src/main/java/com/google/devtools/build/lib:shell",
+        "//src/main/java/com/google/devtools/build/lib:skylarkinterface",
         "//src/main/java/com/google/devtools/build/lib:syntax",
         "//src/main/java/com/google/devtools/build/lib:vfs",
         "//src/main/java/com/google/devtools/build/lib/actions",