[ScanDependency] Handle -Xcc options that affects module generation

Make sure the `-Xcc` options to the scanner are correctly considered
when creating ClangImporterCC1 arguments for constructed swift interface
compilation job. Under directcc1 mode, `-Xcc` options should be used to
constructed sub-invocation but should not be added to GenericArgs for
constructing interface compilation jobs.

rdar://128873665

Author: cachemeifyoucan

include/swift/ClangImporter/ClangImporter.h

@@ -194,7 +194,7 @@ class ClangImporter final : public ClangModuleLoader {
   createClangInvocation(ClangImporter *importer,
                         const ClangImporterOptions &importerOpts,
                         llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
-                        std::vector<std::string> &CC1Args);
+                        const std::vector<std::string> &CC1Args);
 
   ClangImporter(const ClangImporter &) = delete;
   ClangImporter(ClangImporter &&) = delete;

lib/ClangImporter/ClangImporter.cpp

@@ -1216,7 +1216,7 @@ std::optional<std::vector<std::string>> ClangImporter::getClangCC1Arguments(
 std::unique_ptr<clang::CompilerInvocation> ClangImporter::createClangInvocation(
     ClangImporter *importer, const ClangImporterOptions &importerOpts,
     llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
-    std::vector<std::string> &CC1Args) {
+    const std::vector<std::string> &CC1Args) {
   std::vector<const char *> invocationArgs;
   invocationArgs.reserve(CC1Args.size());
   llvm::for_each(CC1Args, [&](const std::string &Arg) {

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1908,16 +1908,11 @@ InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
     // explicit Swift module build tasks will not rely on them and they may be
     // source-target-context-specific and hinder module sharing across
     // compilation source targets.
-    // If using DirectCC1Scan, the command-line reduction is handled inside
-    // `getSwiftExplicitModuleDirectCC1Args()`, there is no need to inherit
-    // anything here as the ExtraArgs from the invocation are clang driver
-    // options, not cc1 options.
     // Clang module dependecies of this Swift dependency will be distinguished
     // by their context hash for different variants, so would still cause a
     // difference in the Swift compile commands, when different.
-    if (!clangImporterOpts.ClangImporterDirectCC1Scan)
-      inheritedParentContextClangArgs =
-          clangImporterOpts.getReducedExtraArgsForSwiftModuleDependency();
+    inheritedParentContextClangArgs =
+        clangImporterOpts.getReducedExtraArgsForSwiftModuleDependency();
     genericSubInvocation.getFrontendOptions()
         .DependencyScanningSubInvocation = true;
   } else if (LoaderOpts.strictImplicitModuleContext ||
@@ -1931,9 +1926,15 @@ InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
     inheritedParentContextClangArgs = clangImporterOpts.ExtraArgs;
   }
   subClangImporterOpts.ExtraArgs = inheritedParentContextClangArgs;
-  for (auto arg : subClangImporterOpts.ExtraArgs) {
-    GenericArgs.push_back("-Xcc");
-    GenericArgs.push_back(ArgSaver.save(arg));
+  // If using DirectCC1Scan, the command-line reduction is handled inside
+  // `getSwiftExplicitModuleDirectCC1Args()`, there is no need to inherit
+  // anything here as the ExtraArgs from the invocation are clang driver
+  // options, not cc1 options.
+  if (!clangImporterOpts.ClangImporterDirectCC1Scan) {
+    for (auto arg : subClangImporterOpts.ExtraArgs) {
+      GenericArgs.push_back("-Xcc");
+      GenericArgs.push_back(ArgSaver.save(arg));
+    }
   }
 
   subClangImporterOpts.EnableClangSPI = clangImporterOpts.EnableClangSPI;

test/CAS/Xcc_objc_direct.swift

@@ -0,0 +1,47 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -scan-dependencies -module-name Test -module-cache-path %t/clang-module-cache -O \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import \
+// RUN:   %t/test.swift -o %t/deps.json -swift-version 5 -cache-compile-job -cas-path %t/cas -Xcc -fobjc-disable-direct-methods-for-testing \
+// RUN:   -file-compilation-dir %t \
+// RUN:   -I %t/include -module-load-mode prefer-serialized
+
+// RUN: %{python} %S/Inputs/BuildCommandExtractor.py %t/deps.json clang:SwiftShims > %t/shims.cmd
+// RUN: %swift_frontend_plain @%t/shims.cmd
+
+// RUN: %{python} %S/Inputs/BuildCommandExtractor.py %t/deps.json clang:B > %t/B.cmd
+// RUN: %swift_frontend_plain @%t/B.cmd
+
+// RUN: %{python} %S/Inputs/BuildCommandExtractor.py %t/deps.json A > %t/A.cmd
+// RUN: %swift_frontend_plain @%t/A.cmd
+
+// RUN: %{python} %S/Inputs/GenerateExplicitModuleMap.py %t/deps.json > %t/map.json
+// RUN: llvm-cas --cas %t/cas --make-blob --data %t/map.json > %t/map.casid
+
+// RUN: %{python} %S/Inputs/BuildCommandExtractor.py %t/deps.json Test > %t/MyApp.cmd
+
+// RUN: %target-swift-frontend \
+// RUN:   -typecheck -cache-compile-job -cas-path %t/cas \
+// RUN:   -swift-version 5 -disable-implicit-swift-modules \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import \
+// RUN:   -module-name Test -explicit-swift-module-map-file @%t/map.casid \
+// RUN:   %t/test.swift @%t/MyApp.cmd
+
+//--- test.swift
+private import A
+
+//--- include/A.swiftinterface
+// swift-interface-format-version: 1.0
+// swift-module-flags: -module-name A -O -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -parse-stdlib -user-module-version 1.0
+import B
+public func a() {}
+
+//--- include/module.modulemap
+module B {
+  header "B.h"
+  export *
+}
+
+//--- include/B.h
+void b(void);