Generate module maps for each objc_* target with compilation support.

This uses CppModuleMap and CppModuleMapAction to generate clang module maps for the target and its transitive dependencies. To enable this feature, you must pass -experimental_objc_enable_module_maps to bazel.

For objc_* targets that need to use the "modules" language features (@import, Swift interop, etc), set the "enable_modules" attribute to 1.

--
MOS_MIGRATED_REVID=103045673

1 files changed, 49 insertions, 7 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
index 59f9b07f67..923ed6c79f 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
@@ -17,8 +17,10 @@ package com.google.devtools.build.lib.rules.objc;
 import com.google.common.base.Optional;
 import com.google.common.base.Preconditions;
 import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.actions.Root;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
 import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.rules.cpp.CppModuleMap;
 import com.google.devtools.build.lib.syntax.Label;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -28,7 +30,7 @@ import com.google.devtools.build.lib.vfs.PathFragment;
  */
 // TODO(bazel-team): This should really be named DerivedArtifacts as it contains methods for
 // final as well as intermediate artifacts.
-final class IntermediateArtifacts {
+public final class IntermediateArtifacts {
 
   /**
    * Extension used on the temporary zipped dsym bundle location. Must contain {@code .dSYM} for
@@ -100,6 +102,16 @@ final class IntermediateArtifacts {
   }
 
   /**
+   * Returns a derived artifact in the genfiles directory obtained by appending some extension to
+   * the end of the {@link PathFragment} corresponding to the owner {@link Label}.
+   */
+  private Artifact appendExtensionInGenfiles(String extension) {
+    PathFragment name = new PathFragment(ruleContext.getLabel().getName());
+    return scopedArtifact(
+        name.replaceName(name.getBaseName() + extension), /* inGenfiles = */ true);
+  }
+
+  /**
    * The output of using {@code actoolzip} to run {@code actool} for a given bundle which is
    * merged under the {@code .app} or {@code .bundle} directory root.
    */
@@ -161,23 +173,34 @@ final class IntermediateArtifacts {
     return appendExtension("_lipobin");
   }
 
-  private Artifact scopedArtifact(PathFragment scopeRelative) {
+  private Artifact scopedArtifact(PathFragment scopeRelative, boolean inGenfiles) {
+    Root root =
+        inGenfiles
+            ? ruleContext.getConfiguration().getGenfilesDirectory()
+            : ruleContext.getConfiguration().getBinDirectory();
     if (scopingLabel.isPresent()) {
       // The path of this artifact will be
       // RULE_PACKAGE/_intermediate_scoped/RULE_LABEL/SCOPING_PACKAGE/SCOPING_LABEL/SCOPERELATIVE
-      return ruleContext.getUniqueDirectoryArtifact("_intermediate_scoped",
-          scopingLabel.get().getPackageIdentifier().getPathFragment()
+      return ruleContext.getUniqueDirectoryArtifact(
+          "_intermediate_scoped",
+          scopingLabel
+              .get()
+              .getPackageIdentifier()
+              .getPathFragment()
               .getRelative(scopingLabel.get().getName())
               .getRelative(scopeRelative),
-          ruleContext.getConfiguration().getBinDirectory());
+          root);
     } else {
       // The path of this artifact will be
       // RULE_PACKAGE/SCOPERELATIVE
-      return ruleContext.getPackageRelativeArtifact(scopeRelative,
-          ruleContext.getConfiguration().getBinDirectory());
+      return ruleContext.getPackageRelativeArtifact(scopeRelative, root);
     }
   }
 
+  private Artifact scopedArtifact(PathFragment scopeRelative) {
+    return scopedArtifact(scopeRelative, /* inGenfiles = */ false);
+  }
+
   /**
    * The {@code .a} file which contains all the compiled sources for a rule.
    */
@@ -339,4 +362,23 @@ final class IntermediateArtifacts {
   public Artifact dotdFile(Artifact source) {
      return inUniqueObjsDir(source, ".d");
   }
+
+  /**
+   * {@link CppModuleMap} that provides the clang module map for this target.
+   */
+  public CppModuleMap moduleMap() {
+    if (!ObjcRuleClasses.objcConfiguration(ruleContext).moduleMapsEnabled()) {
+      throw new IllegalStateException();
+    }
+    String moduleName =
+        ruleContext
+            .getLabel()
+            .toString()
+            .replace("//", "")
+            .replace("/", "_")
+            .replace(":", "_");
+    // To get Swift to pick up module maps, we need to name them "module.modulemap" and have their
+    // parent directory in the module map search paths.
+    return new CppModuleMap(appendExtensionInGenfiles(".modulemaps/module.modulemap"), moduleName);
+  }
 }