[Bridging PCH] Populate bridging lookup table when reading MK_PCH module.

Author: graydon

lib/ClangImporter/ClangImporter.cpp

@@ -662,7 +662,8 @@ ClangImporter::create(ASTContext &ctx,
 
   // Install a Clang module file extension to build Swift name lookup tables.
   invocation->getFrontendOpts().ModuleFileExtensions.push_back(
-      new SwiftNameLookupExtension(importer->Impl.LookupTables,
+      new SwiftNameLookupExtension(importer->Impl.BridgingHeaderLookupTable,
+                                   importer->Impl.LookupTables,
                                    importer->Impl.SwiftContext,
                                    importer->Impl.platformAvailability,
                                    importer->Impl.InferImportAsMember));

lib/ClangImporter/ImporterImpl.h

@@ -1165,16 +1165,18 @@ namespace importer {
 bool shouldSuppressDeclImport(const clang::Decl *decl);
 
 class SwiftNameLookupExtension : public clang::ModuleFileExtension {
+  std::unique_ptr<SwiftLookupTable> &pchLookupTable;
   LookupTableMap &lookupTables;
   ASTContext &swiftCtx;
   const PlatformAvailability &availability;
   const bool inferImportAsMember;
 
 public:
-  SwiftNameLookupExtension(LookupTableMap &tables, ASTContext &ctx,
+  SwiftNameLookupExtension(std::unique_ptr<SwiftLookupTable> &pchLookupTable,
+                           LookupTableMap &tables, ASTContext &ctx,
                            const PlatformAvailability &avail, bool inferIAM)
-      : lookupTables(tables), swiftCtx(ctx), availability(avail),
-        inferImportAsMember(inferIAM) {}
+      : pchLookupTable(pchLookupTable), lookupTables(tables), swiftCtx(ctx),
+        availability(avail), inferImportAsMember(inferIAM) {}
 
   clang::ModuleFileExtensionMetadata getExtensionMetadata() const override;
   llvm::hash_code hashExtension(llvm::hash_code code) const override;

lib/ClangImporter/SwiftLookupTable.cpp

@@ -1688,23 +1688,31 @@ SwiftNameLookupExtension::createExtensionReader(
   assert(metadata.MajorVersion == SWIFT_LOOKUP_TABLE_VERSION_MAJOR);
   assert(metadata.MinorVersion == SWIFT_LOOKUP_TABLE_VERSION_MINOR);
 
-  // Check whether we already have an entry in the set of lookup tables.
-  auto &entry = lookupTables[mod.ModuleName];
-  if (entry) return nullptr;
-
-  // Local function used to remove this entry when the reader goes away.
-  std::string moduleName = mod.ModuleName;
-  auto onRemove = [this, moduleName]() {
-    lookupTables.erase(moduleName);
-  };
+  std::function<void()> onRemove = [](){};
+  std::unique_ptr<SwiftLookupTable> *target = nullptr;
+
+  if (mod.Kind == clang::serialization::MK_PCH) {
+    // PCH imports unconditionally overwrite the provided pchLookupTable.
+    target = &pchLookupTable;
+  } else {
+    // Check whether we already have an entry in the set of lookup tables.
+    target = &lookupTables[mod.ModuleName];
+    if (*target) return nullptr;
+
+    // Local function used to remove this entry when the reader goes away.
+    std::string moduleName = mod.ModuleName;
+    onRemove = [this, moduleName]() {
+      lookupTables.erase(moduleName);
+    };
+  }
 
   // Create the reader.
   auto tableReader = SwiftLookupTableReader::create(this, reader, mod, onRemove,
                                                     stream);
   if (!tableReader) return nullptr;
 
   // Create the lookup table.
-  entry.reset(new SwiftLookupTable(tableReader.get()));
+  target->reset(new SwiftLookupTable(tableReader.get()));
 
   // Return the new reader.
   return std::move(tableReader);