Add implementation deps support for Objective-C (bazelbuild#18372)

src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java

@@ -467,6 +467,11 @@ static Map<Label, Collection<Artifact>> buildLocationMap(
       Iterables.addAll(
           depsDataAndTools, ruleContext.getPrerequisitesIf("deps", FilesToRunProvider.class));
     }
+    if (ruleContext.getRule().isAttrDefined("implementation_deps", BuildType.LABEL_LIST)) {
+      Iterables.addAll(
+          depsDataAndTools,
+          ruleContext.getPrerequisitesIf("implementation_deps", FilesToRunProvider.class));
+    }
     if (allowDataAttributeEntriesInLabel
         && ruleContext.getRule().isAttrDefined("data", BuildType.LABEL_LIST)) {
       Iterables.addAll(

src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java

@@ -111,6 +111,8 @@ static class Builder {
     private final List<CcCompilationContext> ccCompilationContexts = new ArrayList<>();
     private final List<CcLinkingContext> ccLinkingContexts = new ArrayList<>();
     private final List<CcCompilationContext> directCCompilationContexts = new ArrayList<>();
+    private final List<CcCompilationContext> implementationCcCompilationContexts =
+        new ArrayList<>();
     // List of CcLinkingContext to be merged into ObjcProvider, to be done for deps that don't have
     // ObjcProviders.
     // TODO(b/171413861): remove after objc link info migration.
@@ -179,6 +181,13 @@ Builder addCcLinkingContexts(Iterable<CcInfo> ccInfos) {
       return this;
     }
 
+    @CanIgnoreReturnValue
+    Builder addImplementationCcCompilationContexts(Iterable<CcInfo> ccInfos) {
+      ccInfos.forEach(
+          ccInfo -> implementationCcCompilationContexts.add(ccInfo.getCcCompilationContext()));
+      return this;
+    }
+
     @CanIgnoreReturnValue
     Builder addCcInfos(Iterable<CcInfo> ccInfos) {
       addCcCompilationContexts(ccInfos);
@@ -291,6 +300,8 @@ ObjcCommon build() {
           ImmutableList.copyOf(this.ccLinkingContexts);
       ImmutableList<CcCompilationContext> directCCompilationContexts =
           ImmutableList.copyOf(this.directCCompilationContexts);
+      ImmutableList<CcCompilationContext> implementationCcCompilationContexts =
+          ImmutableList.copyOf(this.implementationCcCompilationContexts);
       ImmutableList<CcLinkingContext> ccLinkingContextsForMerging =
           ImmutableList.copyOf(this.ccLinkingContextsForMerging);
 
@@ -310,7 +321,8 @@ ObjcCommon build() {
           .addDirectCcCompilationContexts(directCCompilationContexts)
           // TODO(bazel-team): This pulls in stl via
           // CcCompilationHelper.getStlCcCompilationContext(), but probably shouldn't.
-          .addCcCompilationContexts(ccCompilationContexts);
+          .addCcCompilationContexts(ccCompilationContexts)
+          .addImplementationCcCompilationContexts(implementationCcCompilationContexts);
 
       for (CcLinkingContext ccLinkingContext : ccLinkingContextsForMerging) {
         ImmutableList<String> linkOpts = ccLinkingContext.getFlattenedUserLinkFlags();

src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCompilationContext.java

@@ -53,6 +53,7 @@ public final class ObjcCompilationContext implements StarlarkValue {
   private final ImmutableList<PathFragment> strictDependencyIncludes;
   private final ImmutableList<CcCompilationContext> directCcCompilationContexts;
   private final ImmutableList<CcCompilationContext> ccCompilationContexts;
+  private final ImmutableList<CcCompilationContext> implementationCcCompilationContexts;
 
   ObjcCompilationContext(
       Iterable<String> defines,
@@ -64,7 +65,8 @@ public final class ObjcCompilationContext implements StarlarkValue {
       Iterable<PathFragment> quoteIncludes,
       Iterable<PathFragment> strictDependencyIncludes,
       Iterable<CcCompilationContext> directCcCompilationContexts,
-      Iterable<CcCompilationContext> ccCompilationContexts) {
+      Iterable<CcCompilationContext> ccCompilationContexts,
+      Iterable<CcCompilationContext> implementationCcCompilationContexts) {
     this.defines = ImmutableList.copyOf(defines);
     this.publicHeaders = ImmutableList.copyOf(publicHeaders);
     this.publicTextualHeaders = ImmutableList.copyOf(publicTextualHeaders);
@@ -75,6 +77,8 @@ public final class ObjcCompilationContext implements StarlarkValue {
     this.strictDependencyIncludes = ImmutableList.copyOf(strictDependencyIncludes);
     this.directCcCompilationContexts = ImmutableList.copyOf(directCcCompilationContexts);
     this.ccCompilationContexts = ImmutableList.copyOf(ccCompilationContexts);
+    this.implementationCcCompilationContexts =
+        ImmutableList.copyOf(implementationCcCompilationContexts);
   }
 
   public ImmutableList<String> getDefines() {
@@ -159,11 +163,23 @@ public ImmutableList<CcCompilationContext> getCcCompilationContexts() {
     return ccCompilationContexts;
   }
 
+  public ImmutableList<CcCompilationContext> getImplementationCcCompilationContexts() {
+    return implementationCcCompilationContexts;
+  }
+
   @StarlarkMethod(name = "cc_compilation_contexts", documented = false, structField = true)
   public Sequence<CcCompilationContext> getCcCompilationContextsForStarlark() {
     return StarlarkList.immutableCopyOf(getCcCompilationContexts());
   }
 
+  @StarlarkMethod(
+      name = "implementation_cc_compilation_contexts",
+      documented = false,
+      structField = true)
+  public Sequence<CcCompilationContext> getImplementationCcCompilationContextsForStarlark() {
+    return StarlarkList.immutableCopyOf(getImplementationCcCompilationContexts());
+  }
+
   public CcCompilationContext createCcCompilationContext() {
     CcCompilationContext.Builder builder =
         CcCompilationContext.builder(
@@ -200,6 +216,8 @@ static class Builder {
     private final List<PathFragment> strictDependencyIncludes = new ArrayList<>();
     private final List<CcCompilationContext> directCcCompilationContexts = new ArrayList<>();
     private final List<CcCompilationContext> ccCompilationContexts = new ArrayList<>();
+    private final List<CcCompilationContext> implementationCcCompilationContexts =
+        new ArrayList<>();
 
     Builder() {}
 
@@ -266,6 +284,13 @@ public Builder addDirectCcCompilationContexts(
       return this;
     }
 
+    @CanIgnoreReturnValue
+    public Builder addImplementationCcCompilationContexts(
+        Iterable<CcCompilationContext> ccCompilationContexts) {
+      Iterables.addAll(this.implementationCcCompilationContexts, ccCompilationContexts);
+      return this;
+    }
+
     @CanIgnoreReturnValue
     public Builder addCcCompilationContext(CcCompilationContext ccCompilationContext) {
       this.ccCompilationContexts.add(ccCompilationContext);
@@ -283,7 +308,8 @@ ObjcCompilationContext build() {
           quoteIncludes,
           strictDependencyIncludes,
           directCcCompilationContexts,
-          ccCompilationContexts);
+          ccCompilationContexts,
+          implementationCcCompilationContexts);
     }
   }
 }

src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java

@@ -453,6 +453,19 @@ Header file to prepend to every source file being compiled (both arc
                   .direct_compile_time_input()
                   .mandatoryProviders(AppleDynamicFrameworkInfo.STARLARK_CONSTRUCTOR.id())
                   .allowedFileTypes())
+          /* <!-- #BLAZE_RULE($objc_compiling_rule).ATTRIBUTE(implementation_deps) -->
+          The list of other libraries that the library target depends on. Unlike with
+          <code>deps</code>, the headers and include paths of these libraries (and all their
+          transitive deps) are only used for compilation of this library, and not libraries that
+          depend on it. Libraries specified with <code>implementation_deps</code> are still linked
+          in binary targets that depend on this library.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(
+              attr("implementation_deps", LABEL_LIST)
+                  .direct_compile_time_input()
+                  .allowedRuleClasses(ALLOWED_CC_DEPS_RULE_CLASSES)
+                  .mandatoryProviders(ObjcProvider.STARLARK_CONSTRUCTOR.id())
+                  .allowedFileTypes())
           /* <!-- #BLAZE_RULE($objc_compiling_rule).ATTRIBUTE(defines) -->
           Extra <code>-D</code> flags to pass to the compiler. They should be in
           the form <code>KEY=VALUE</code> or simply <code>KEY</code> and are

src/main/java/com/google/devtools/build/lib/rules/objc/ObjcStarlarkInternal.java

@@ -268,6 +268,11 @@ public InstrumentedFilesInfo createInstrumentedFilesInfo(
             positional = false,
             defaultValue = "[]",
             named = true),
+        @Param(
+            name = "implementation_cc_compilation_contexts",
+            positional = false,
+            defaultValue = "[]",
+            named = true),
         @Param(name = "defines", positional = false, defaultValue = "[]", named = true),
         @Param(name = "includes", positional = false, defaultValue = "[]", named = true),
       })
@@ -278,6 +283,7 @@ public ObjcCompilationContext createCompilationContext(
       Sequence<?> providers,
       Sequence<?> directCcCompilationContexts,
       Sequence<?> ccCompilationContexts,
+      Sequence<?> implementationCcCompilationContexts,
       Sequence<?> defines,
       Sequence<?> includes)
       throws InterruptedException, EvalException {
@@ -293,6 +299,11 @@ public ObjcCompilationContext createCompilationContext(
         .addCcCompilationContexts(
             Sequence.cast(
                 ccCompilationContexts, CcCompilationContext.class, "cc_compilation_contexts"))
+        .addImplementationCcCompilationContexts(
+            Sequence.cast(
+                implementationCcCompilationContexts,
+                CcCompilationContext.class,
+                "implementation_cc_compilation_contexts"))
         .addDefines(Sequence.cast(defines, String.class, "defines"))
         .addIncludes(
             Sequence.cast(includes, String.class, "includes").stream()

src/main/starlark/builtins_bzl/common/objc/compilation_support.bzl

@@ -72,6 +72,7 @@ def _build_common_variables(
         empty_compilation_artifacts = False,
         deps = [],
         runtime_deps = [],
+        implementation_deps = [],
         extra_disabled_features = [],
         extra_enabled_features = [],
         extra_import_libraries = [],
@@ -95,6 +96,7 @@ def _build_common_variables(
         compilation_artifacts = compilation_artifacts,
         deps = deps,
         runtime_deps = runtime_deps,
+        implementation_deps = implementation_deps,
         intermediate_artifacts = intermediate_artifacts,
         alwayslink = alwayslink,
         has_module_map = has_module_map,
@@ -193,6 +195,7 @@ def _compile(
         system_includes = objc_compilation_context.system_includes,
         quote_includes = objc_compilation_context.quote_includes,
         compilation_contexts = objc_compilation_context.cc_compilation_contexts,
+        implementation_compilation_contexts = objc_compilation_context.implementation_cc_compilation_contexts,
         user_compile_flags = user_compile_flags,
         grep_includes = _get_grep_includes(common_variables.ctx),
         module_map = module_map,

src/main/starlark/builtins_bzl/common/objc/objc_common.bzl

@@ -28,6 +28,7 @@ def _create_context_and_provider(
         extra_import_libraries,
         deps,
         runtime_deps,
+        implementation_deps,
         attr_linkopts):
     objc_providers = []
     cc_compilation_contexts = []
@@ -57,6 +58,31 @@ def _create_context_and_provider(
         if CcInfo in runtime_dep:
             cc_compilation_contexts.append(runtime_dep[CcInfo].compilation_context)
 
+    implementation_cc_compilation_contexts = []
+    for impl_dep in implementation_deps:
+        if apple_common.Objc in impl_dep:
+            # For implementation deps, we only need to propagate linker inputs
+            # with Objc provider, but no compilation artifacts
+            # (eg module_map, umbrella_header).
+            implementation_dep_objc_provider_kwargs = {
+                "force_load_library": impl_dep[apple_common.Objc].force_load_library,
+                "imported_library": impl_dep[apple_common.Objc].imported_library,
+                "library": impl_dep[apple_common.Objc].library,
+                "linkopt": impl_dep[apple_common.Objc].linkopt,
+                "sdk_dylib": impl_dep[apple_common.Objc].sdk_dylib,
+                "sdk_framework": impl_dep[apple_common.Objc].sdk_framework,
+                "source": impl_dep[apple_common.Objc].source,
+                "weak_sdk_framework": impl_dep[apple_common.Objc].weak_sdk_framework,
+            }
+            objc_provider = apple_common.new_objc_provider(**implementation_dep_objc_provider_kwargs)
+            objc_providers.append(objc_provider)
+        elif CcInfo in impl_dep:
+            cc_linking_contexts_for_merging.append(impl_dep[CcInfo].linking_context)
+
+        if CcInfo in impl_dep:
+            implementation_cc_compilation_contexts.append(impl_dep[CcInfo].compilation_context)
+            cc_linking_contexts.append(impl_dep[CcInfo].linking_context)
+
     link_order_keys = [
         "imported_library",
         "cc_library",
@@ -82,6 +108,7 @@ def _create_context_and_provider(
     objc_compilation_context_kwargs = {
         "providers": objc_providers + runtime_objc_providers,
         "cc_compilation_contexts": cc_compilation_contexts,
+        "implementation_cc_compilation_contexts": implementation_cc_compilation_contexts,
         "public_hdrs": [],
         "private_hdrs": [],
         "public_textual_hdrs": [],

src/main/starlark/builtins_bzl/common/objc/objc_library.bzl

@@ -45,6 +45,7 @@ def _objc_library_impl(ctx):
         use_pch = True,
         deps = ctx.attr.deps,
         runtime_deps = ctx.attr.runtime_deps,
+        implementation_deps = ctx.attr.implementation_deps,
         attr_linkopts = ctx.attr.linkopts,
         alwayslink = ctx.attr.alwayslink,
     )
@@ -89,6 +90,7 @@ objc_library = rule(
     attrs = common_attrs.union(
         {
             "data": attr.label_list(allow_files = True),
+            "implementation_deps": attr.label_list(providers = [CcInfo], allow_files = False),
         },
         common_attrs.CC_TOOLCHAIN_RULE,
         common_attrs.LICENSES,

src/test/java/com/google/devtools/build/lib/rules/objc/ObjcLibraryTest.java

@@ -128,15 +128,21 @@ public void testCompilesSources() throws Exception {
         .write();
 
     createLibraryTargetWriter("//objc/lib2")
+        .setAndCreateFiles("srcs", "b.m")
+        .setAndCreateFiles("hdrs", "private.h")
+        .write();
+
+    createLibraryTargetWriter("//objc/lib3")
         .setAndCreateFiles("srcs", "a.m")
         .setAndCreateFiles("hdrs", "hdr.h")
         .setList("deps", "//objc/lib1")
+        .setList("implementation_deps", "//objc/lib2")
         .write();
 
     createLibraryTargetWriter("//objc:x")
         .setAndCreateFiles("srcs", "a.m", "private.h")
         .setAndCreateFiles("hdrs", "hdr.h")
-        .setList("deps", "//objc/lib2:lib2")
+        .setList("deps", "//objc/lib3:lib3")
         .write();
 
     CppCompileAction compileA = (CppCompileAction) compileAction("//objc:x", "a.o");
@@ -1077,20 +1083,34 @@ public void testProvidesObjcLibraryAndHeaders() throws Exception {
             .setAndCreateFiles("srcs", "a.m", "b.m", "private.h")
             .setAndCreateFiles("hdrs", "a.h", "b.h")
             .write();
+    ConfiguredTarget impltarget =
+        createLibraryTargetWriter("//objc_impl:lib")
+            .setAndCreateFiles("srcs", "a.m", "b.m", "private.h")
+            .setAndCreateFiles("hdrs", "a.h", "b.h")
+            .write();
     ConfiguredTarget depender =
-        createLibraryTargetWriter("//objc2:lib")
+        createLibraryTargetWriter("//objc_depender:lib")
             .setAndCreateFiles("srcs", "a.m", "b.m", "private.h")
             .setAndCreateFiles("hdrs", "c.h", "d.h")
             .setList("deps", "//objc:lib")
+            .setList("implementation_deps", "//objc_impl:lib")
             .write();
     assertThat(getArifactPaths(target, LIBRARY)).containsExactly("objc/liblib.a");
-    assertThat(getArifactPaths(depender, LIBRARY)).containsExactly(
-        "objc/liblib.a", "objc2/liblib.a");
+    assertThat(getArifactPaths(depender, LIBRARY))
+        .containsExactly("objc/liblib.a", "objc_impl/liblib.a", "objc_depender/liblib.a");
+    assertThat(getArifactPaths(impltarget, LIBRARY)).containsExactly("objc_impl/liblib.a");
     assertThat(getArifactPathsOfHeaders(target))
         .containsExactly("objc/a.h", "objc/b.h", "objc/private.h");
+    assertThat(getArifactPathsOfHeaders(impltarget))
+        .containsExactly("objc_impl/a.h", "objc_impl/b.h", "objc_impl/private.h");
     assertThat(getArifactPathsOfHeaders(depender))
         .containsExactly(
-            "objc/a.h", "objc/b.h", "objc/private.h", "objc2/c.h", "objc2/d.h", "objc2/private.h");
+            "objc/a.h",
+            "objc/b.h",
+            "objc/private.h",
+            "objc_depender/c.h",
+            "objc_depender/d.h",
+            "objc_depender/private.h");
   }
 
   private static Iterable<String> getArifactPaths(