Allow creation of an "umbrella directory" module map

Summary:
This adds a separate mode for module map generation that uses an umbrella directory declaration, rather than an umbrella header declaration.

This fits Buck's general approach to headers better - it's kind of like an autoglob for every header in the library, without the need to either generate or manually maintain a valid umbrella header.

It's implemented by adding a new `ModuleMapMode` enum, and a new case to `HeaderMode` to differentiate between the two associated forms of module maps. I decided to have it specified at the `.buckconfig` level, rather than per-library, as this is simpler and is sufficient for the use-case.

Reviewed By: williamtwilson

shipit-source-id: 10842bbd24

Author: natestedman

src/com/facebook/buck/apple/AppleConfig.java

@@ -16,6 +16,7 @@
 
 package com.facebook.buck.apple;
 
+import com.facebook.buck.apple.clang.ModuleMapMode;
 import com.facebook.buck.apple.toolchain.ApplePlatform;
 import com.facebook.buck.core.config.BuckConfig;
 import com.facebook.buck.core.config.ConfigView;
@@ -462,6 +463,13 @@ public boolean shouldWorkAroundDsymutilLTOStackOverflowBug() {
         APPLE_SECTION, "work_around_dsymutil_lto_stack_overflow_bug", false);
   }
 
+  /** @return The module map mode to use for modular libraries. */
+  public ModuleMapMode moduleMapMode() {
+    return delegate
+        .getEnum(APPLE_SECTION, "modulemap_mode", ModuleMapMode.class)
+        .orElse(ModuleMapMode.UMBRELLA_HEADER);
+  }
+
   public Path shellPath() {
     return delegate.getPath(APPLE_SECTION, "xcode_build_script_shell").orElse(Paths.get("/bin/sh"));
   }

src/com/facebook/buck/apple/AppleLibraryDescription.java

@@ -635,7 +635,7 @@ BuildRule requireSingleArchUnstrippedBuildRule(
         && libType.isPresent()
         && libType.get().equals(Type.EXPORTED_HEADERS)
         && headerMode.isPresent()
-        && headerMode.get().equals(HeaderMode.SYMLINK_TREE_WITH_MODULEMAP)) {
+        && headerMode.get().includesModuleMap()) {
       return createExportedModuleSymlinkTreeBuildRule(
           buildTarget,
           context.getProjectFilesystem(),
@@ -711,7 +711,7 @@ private HeaderSymlinkTree createExportedModuleSymlinkTreeBuildRule(
     return CxxDescriptionEnhancer.createHeaderSymlinkTree(
         buildTarget,
         projectFilesystem,
-        HeaderMode.SYMLINK_TREE_WITH_MODULEMAP,
+        HeaderMode.forModuleMapMode(appleConfig.moduleMapMode()),
         headers.build(),
         HeaderVisibility.PUBLIC);
   }
@@ -733,7 +733,11 @@ private HeaderSymlinkTree createUnderlyingModuleSymlinkTreeBuildRule(
 
     Path root = BuildTargetPaths.getGenPath(projectFilesystem, buildTarget, "%s");
     return CxxPreprocessables.createHeaderSymlinkTreeBuildRule(
-        buildTarget, projectFilesystem, root, headers, HeaderMode.SYMLINK_TREE_WITH_MODULEMAP);
+        buildTarget,
+        projectFilesystem,
+        root,
+        headers,
+        HeaderMode.forModuleMapMode(appleConfig.moduleMapMode()));
   }
 
   <U> Optional<U> createMetadataForLibrary(
@@ -910,7 +914,7 @@ private <U> Optional<U> createCxxPreprocessorInputMetadata(
                     .withAppendedFlavors(
                         CxxLibraryDescription.Type.EXPORTED_HEADERS.getFlavor(),
                         platformEntry.getKey(),
-                        HeaderMode.SYMLINK_TREE_WITH_MODULEMAP.getFlavor()));
+                        HeaderMode.forModuleMapMode(appleConfig.moduleMapMode()).getFlavor()));
     cxxPreprocessorInputBuilder.addIncludes(
         CxxSymlinkTreeHeaders.from(symlinkTree, CxxPreprocessables.IncludeType.LOCAL));
     CxxPreprocessorInput cxxPreprocessorInput = cxxPreprocessorInputBuilder.build();

src/com/facebook/buck/apple/BUCK

@@ -20,6 +20,7 @@ java_library_with_plugins(
     ],
     deps = [
         "//src/com/facebook/buck/android/toolchain/ndk:ndk",
+        "//src/com/facebook/buck/apple/clang:clang",
         "//src/com/facebook/buck/apple/platform_type:type",
         "//src/com/facebook/buck/apple/simulator:simulator",
         "//src/com/facebook/buck/apple/toolchain:toolchain",

src/com/facebook/buck/apple/clang/ModuleMapFactory.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2014-present Facebook, Inc.
+ *
+ * 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.facebook.buck.apple.clang;
+
+/**
+ * Creates module map instances.
+ *
+ * <p>Use this instead of directly creating UmbrellaHeaderModuleMap or UmbrellaDirectoryModuleMap
+ * instances.
+ */
+public class ModuleMapFactory {
+
+  /**
+   * Creates a module map.
+   *
+   * @param moduleName The name of the module.
+   * @param moduleMapMode The module map mode to use.
+   * @param swiftMode The Swift mode to use for umbrella header module maps. This parameter is
+   *     unused with umbrella directory module maps.
+   * @return A module map instance.
+   */
+  public static ModuleMap createModuleMap(
+      String moduleName, ModuleMapMode moduleMapMode, UmbrellaHeaderModuleMap.SwiftMode swiftMode) {
+    switch (moduleMapMode) {
+      case UMBRELLA_HEADER:
+        return new UmbrellaHeaderModuleMap(moduleName, swiftMode);
+      case UMBRELLA_DIRECTORY:
+        return new UmbrellaDirectoryModuleMap(moduleName);
+    }
+
+    throw new RuntimeException();
+  }
+}

src/com/facebook/buck/apple/clang/ModuleMapMode.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2014-present Facebook, Inc.
+ *
+ * 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.facebook.buck.apple.clang;
+
+/** Enumerates the module map generation modes that Buck supports. */
+public enum ModuleMapMode {
+  /** Generate a module map that requires an umbrella header. */
+  UMBRELLA_HEADER,
+
+  /** Generate a module map that uses the library's headers in an umbrella directory. */
+  UMBRELLA_DIRECTORY,
+}

src/com/facebook/buck/apple/clang/UmbrellaDirectoryModuleMap.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2014-present Facebook, Inc.
+ *
+ * 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.facebook.buck.apple.clang;
+
+import com.google.common.base.Objects;
+import javax.annotation.Nullable;
+import org.stringtemplate.v4.ST;
+
+/**
+ * A module map using an umbrella directory, rather than an umbrella header. This removes the need
+ * to maintain or generate an umbrella header: all exported headers in the library will be included
+ * in the module automatically.
+ */
+public class UmbrellaDirectoryModuleMap implements ModuleMap {
+  private final String moduleName;
+
+  @Nullable private String generatedModule;
+  private static final String template =
+      "module <module_name> {\n"
+          + "    umbrella \".\"\n"
+          + "\n"
+          + "    module * { export * }\n"
+          + "}\n"
+          + "\n";
+
+  public UmbrellaDirectoryModuleMap(String moduleName) {
+    this.moduleName = moduleName;
+  }
+
+  @Override
+  public String render() {
+    if (this.generatedModule == null) {
+      ST st = new ST(template).add("module_name", moduleName);
+      this.generatedModule = st.render();
+    }
+    return this.generatedModule;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (!(obj instanceof UmbrellaDirectoryModuleMap)) {
+      return false;
+    }
+    UmbrellaDirectoryModuleMap that = (UmbrellaDirectoryModuleMap) obj;
+    return Objects.equal(this.moduleName, that.moduleName);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hashCode(moduleName);
+  }
+}

src/com/facebook/buck/cxx/CxxPreprocessables.java

@@ -16,6 +16,7 @@
 
 package com.facebook.buck.cxx;
 
+import com.facebook.buck.apple.clang.ModuleMapMode;
 import com.facebook.buck.core.model.BuildTarget;
 import com.facebook.buck.core.rules.ActionGraphBuilder;
 import com.facebook.buck.core.rules.BuildRule;
@@ -138,8 +139,12 @@ public static HeaderSymlinkTree createHeaderSymlinkTreeBuildRule(
     switch (headerMode) {
       case SYMLINK_TREE_WITH_HEADER_MAP:
         return HeaderSymlinkTreeWithHeaderMap.create(target, filesystem, root, links);
-      case SYMLINK_TREE_WITH_MODULEMAP:
-        return HeaderSymlinkTreeWithModuleMap.create(target, filesystem, root, links);
+      case SYMLINK_TREE_WITH_UMBRELLA_HEADER_MODULEMAP:
+        return HeaderSymlinkTreeWithModuleMap.create(
+            target, filesystem, root, links, ModuleMapMode.UMBRELLA_HEADER);
+      case SYMLINK_TREE_WITH_UMBRELLA_DIRECTORY_MODULEMAP:
+        return HeaderSymlinkTreeWithModuleMap.create(
+            target, filesystem, root, links, ModuleMapMode.UMBRELLA_DIRECTORY);
       case HEADER_MAP_ONLY:
         return new DirectHeaderMap(target, filesystem, root, links);
       default:

src/com/facebook/buck/cxx/toolchain/HeaderMode.java

@@ -16,6 +16,7 @@
 
 package com.facebook.buck.cxx.toolchain;
 
+import com.facebook.buck.apple.clang.ModuleMapMode;
 import com.facebook.buck.core.model.Flavor;
 import com.facebook.buck.core.model.FlavorConvertible;
 import com.facebook.buck.core.model.InternalFlavor;
@@ -34,9 +35,16 @@ public enum HeaderMode implements FlavorConvertible {
   SYMLINK_TREE_WITH_HEADER_MAP,
   /**
    * Creates the tree of symbolic links of headers and creates a module map that references the
-   * symbolic links to the headers.
+   * symbolic links to the headers. The generated module map will refer to an umbrella header, with
+   * the same name as the library.
+   */
+  SYMLINK_TREE_WITH_UMBRELLA_HEADER_MODULEMAP,
+  /**
+   * Creates the tree of symbolic links of headers and creates a module map that references the
+   * symbolic links to the headers. The generated module map will refer to an umbrella directory,
+   * avoiding the need for a valid and complete umbrella header.
    */
-  SYMLINK_TREE_WITH_MODULEMAP,
+  SYMLINK_TREE_WITH_UMBRELLA_DIRECTORY_MODULEMAP,
   ;
 
   private final Flavor flavor;
@@ -54,4 +62,40 @@ public enum HeaderMode implements FlavorConvertible {
   public Flavor getFlavor() {
     return flavor;
   }
+
+  /**
+   * Returns the appropriate header mode for module map mode.
+   *
+   * @param moduleMapMode The module map mode to convert.
+   * @return The equivalent header mode.
+   */
+  public static HeaderMode forModuleMapMode(ModuleMapMode moduleMapMode) {
+    switch (moduleMapMode) {
+      case UMBRELLA_HEADER:
+        return SYMLINK_TREE_WITH_UMBRELLA_HEADER_MODULEMAP;
+      case UMBRELLA_DIRECTORY:
+        return SYMLINK_TREE_WITH_UMBRELLA_DIRECTORY_MODULEMAP;
+    }
+
+    throw new RuntimeException("Unexpected value of enum ModuleMapMode");
+  }
+
+  /**
+   * Returns whether or not the header mode will include a module map.
+   *
+   * @return true if the header mode will include a module map, otherwise false.
+   */
+  public boolean includesModuleMap() {
+    switch (this) {
+      case SYMLINK_TREE_ONLY:
+      case SYMLINK_TREE_WITH_HEADER_MAP:
+      case HEADER_MAP_ONLY:
+        return false;
+      case SYMLINK_TREE_WITH_UMBRELLA_HEADER_MODULEMAP:
+      case SYMLINK_TREE_WITH_UMBRELLA_DIRECTORY_MODULEMAP:
+        return true;
+    }
+
+    throw new RuntimeException("Unexpected value of enum HeaderMode");
+  }
 }

src/com/facebook/buck/cxx/toolchain/HeaderSymlinkTreeWithModuleMap.java

@@ -16,6 +16,8 @@
 
 package com.facebook.buck.cxx.toolchain;
 
+import com.facebook.buck.apple.clang.ModuleMapFactory;
+import com.facebook.buck.apple.clang.ModuleMapMode;
 import com.facebook.buck.apple.clang.UmbrellaHeader;
 import com.facebook.buck.apple.clang.UmbrellaHeaderModuleMap;
 import com.facebook.buck.core.build.buildable.context.BuildableContext;
@@ -38,24 +40,29 @@
 public final class HeaderSymlinkTreeWithModuleMap extends HeaderSymlinkTree {
 
   @AddToRuleKey private final Optional<String> moduleName;
+  @AddToRuleKey private final ModuleMapMode moduleMapMode;
 
   private HeaderSymlinkTreeWithModuleMap(
       BuildTarget target,
       ProjectFilesystem filesystem,
       Path root,
       ImmutableMap<Path, SourcePath> links,
-      Optional<String> moduleName) {
+      Optional<String> moduleName,
+      ModuleMapMode moduleMapMode) {
     super(target, filesystem, root, links);
     this.moduleName = moduleName;
+    this.moduleMapMode = moduleMapMode;
   }
 
   public static HeaderSymlinkTreeWithModuleMap create(
       BuildTarget target,
       ProjectFilesystem filesystem,
       Path root,
-      ImmutableMap<Path, SourcePath> links) {
+      ImmutableMap<Path, SourcePath> links,
+      ModuleMapMode moduleMapMode) {
     Optional<String> moduleName = getModuleName(links);
-    return new HeaderSymlinkTreeWithModuleMap(target, filesystem, root, links, moduleName);
+    return new HeaderSymlinkTreeWithModuleMap(
+        target, filesystem, root, links, moduleName, moduleMapMode);
   }
 
   @Override
@@ -81,8 +88,9 @@ public ImmutableList<Step> getBuildSteps(
               new ModuleMapStep(
                   getProjectFilesystem(),
                   moduleMapPath(getProjectFilesystem(), getBuildTarget(), moduleName),
-                  new UmbrellaHeaderModuleMap(
+                  ModuleMapFactory.createModuleMap(
                       moduleName,
+                      moduleMapMode,
                       containsSwiftHeader(paths, moduleName)
                           ? UmbrellaHeaderModuleMap.SwiftMode.INCLUDE_SWIFT_HEADER
                           : UmbrellaHeaderModuleMap.SwiftMode.NO_SWIFT)));