[cxx-interop] Fix SIL deserialization error

Author: egorzhdan

lib/ClangImporter/ImportDecl.cpp

@@ -9519,6 +9519,12 @@ Decl *ClangImporter::Implementation::importDeclAndCacheImpl(
   if (!SuperfluousTypedefsAreTransparent && TypedefIsSuperfluous)
     return nullptr;
 
+  if (ClangDecl->getDeclContext()->isNamespace()) {
+    addEntryToLookupTable(*BridgingHeaderLookupTable,
+                          const_cast<clang::NamedDecl *>(ClangDecl),
+                          getNameImporter());
+  }
+
   return Result;
 }
 

lib/Serialization/Deserialization.cpp

@@ -5141,6 +5141,7 @@ getActualSILFunctionTypeRepresentation(uint8_t rep) {
   CASE(Method)
   CASE(ObjCMethod)
   CASE(WitnessMethod)
+  CASE(CXXMethod)
 #undef CASE
   default:
     return None;