[BridgingHeaderChaining] Bind bridging header module when load module

include/swift/ClangImporter/ClangImporter.h

@@ -428,6 +428,16 @@ class ClangImporter final : public ClangModuleLoader {
                             bool trackParsedSymbols = false,
                             bool implicitImport = false);
 
+  /// Bind the bridging header content to the module.
+  ///
+  /// \param adapter The module that depends on the contents of this header.
+  /// \param diagLoc A location to attach any diagnostics to if import fails.
+  ///
+  /// \returns true if there was an error importing the header.
+  ///
+  /// \sa importBridgingHeader
+  bool bindBridgingHeader(ModuleDecl *adapter, SourceLoc diagLoc);
+
   /// Returns the module that contains imports and declarations from all loaded
   /// Objective-C header files.
   ///

lib/ClangImporter/ClangImporter.cpp

@@ -1869,12 +1869,7 @@ bool ClangImporter::importBridgingHeader(StringRef header, ModuleDecl *adapter,
                                          bool trackParsedSymbols,
                                          bool implicitImport) {
   if (isPCHFilenameExtension(header)) {
-    Impl.ImportedHeaderOwners.push_back(adapter);
-    // We already imported this with -include-pch above, so we should have
-    // collected a bunch of PCH-encoded module imports that we just need to
-    // replay in handleDeferredImports.
-    Impl.handleDeferredImports(diagLoc);
-    return false;
+    return bindBridgingHeader(adapter, diagLoc);
   }
 
   clang::FileManager &fileManager = Impl.Instance->getFileManager();
@@ -1901,6 +1896,15 @@ bool ClangImporter::importBridgingHeader(StringRef header, ModuleDecl *adapter,
                            std::move(sourceBuffer), implicitImport);
 }
 
+bool ClangImporter::bindBridgingHeader(ModuleDecl *adapter, SourceLoc diagLoc) {
+  Impl.ImportedHeaderOwners.push_back(adapter);
+  // We already imported this with -include-pch above, so we should have
+  // collected a bunch of PCH-encoded module imports that we just need to
+  // replay in handleDeferredImports.
+  Impl.handleDeferredImports(diagLoc);
+  return false;
+}
+
 static llvm::Expected<llvm::cas::ObjectRef>
 setupIncludeTreeInput(clang::CompilerInvocation &invocation,
                       StringRef headerPath, StringRef pchIncludeTree) {

lib/Serialization/ModuleFile.cpp

@@ -165,15 +165,18 @@ ModuleFile::loadDependenciesForFileContext(const FileUnit *file,
     if (dependency.isHeader()) {
       // The path may be empty if the file being loaded is a partial AST,
       // and the current compiler invocation is a merge-modules step.
-      if (!dependency.Core.RawPath.empty() &&
-          !M->getASTContext().SearchPathOpts.BridgingHeaderChaining) {
+      if (!dependency.Core.RawPath.empty()) {
+        // If using bridging header chaining, just bind the entire bridging
+        // header pch to the module. Otherwise, import the header.
         bool hadError =
-            clangImporter->importHeader(dependency.Core.RawPath,
-                                        file->getParentModule(),
-                                        Core->importedHeaderInfo.fileSize,
-                                        Core->importedHeaderInfo.fileModTime,
-                                        Core->importedHeaderInfo.contents,
-                                        diagLoc);
+            M->getASTContext().SearchPathOpts.BridgingHeaderChaining
+                ? clangImporter->bindBridgingHeader(file->getParentModule(),
+                                                    diagLoc)
+                : clangImporter->importHeader(
+                      dependency.Core.RawPath, file->getParentModule(),
+                      Core->importedHeaderInfo.fileSize,
+                      Core->importedHeaderInfo.fileModTime,
+                      Core->importedHeaderInfo.contents, diagLoc);
         if (hadError)
           return error(Status::FailedToLoadBridgingHeader);
       }

test/ScanDependencies/bridging-header-autochaining.swift

@@ -180,6 +180,8 @@ extension A {
     public func testA() {}
 }
 
+public class AB : B {}
+
 //--- user2.swift
 import Test