[Frontend] A]llow loading the adjacent module for _StringProcessing

Author: xymus

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -676,7 +676,7 @@ class ModuleInterfaceLoaderImpl {
     std::pair<std::string, std::string> result;
     // Should we attempt to load a swiftmodule adjacent to the swiftinterface?
     bool shouldLoadAdjacentModule = !ctx.IgnoreAdjacentModules ||
-      moduleName == STDLIB_NAME;
+      moduleName == STDLIB_NAME || moduleName == SWIFT_STRING_PROCESSING_NAME;
 
     // Don't use the adjacent swiftmodule for frameworks from the public
     // Frameworks folder of the SDK.

lib/Serialization/SerializedModuleLoader.cpp

@@ -446,7 +446,8 @@ std::error_code ImplicitSerializedModuleLoader::findModuleFilesInDirectory(
          "Module and Module Doc buffer must both be initialized or NULL");
 
   if (LoadMode == ModuleLoadingMode::OnlyInterface ||
-      (Ctx.IgnoreAdjacentModules && ModuleID.Item.str() != STDLIB_NAME))
+      (Ctx.IgnoreAdjacentModules && ModuleID.Item.str() != STDLIB_NAME &&
+       ModuleID.Item.str() !=SWIFT_STRING_PROCESSING_NAME))
     return std::make_error_code(std::errc::not_supported);
 
   auto ModuleErr = openModuleFile(ModuleID, BaseName, ModuleBuffer);