TableGen/SearchableTables: Cast enums to unsigned in generated code

[nhaehnle]

Summary

This should fix signedness warnings when compiling with MSVC.

Change-Id: I4664cce0ba91e9b42d21a86fd4a7e82f2320c451

[RKSimon]

LGTM - thanks

utils/TableGen/SearchableTableEmitter.cpp

void SearchableTableEmitter::emitLookupFunction(const GenericTable &Table,
   OS << "    [](const " << IndexTypeName << " &LHS, const KeyType &RHS) {\n";
 
   for (const auto &Field : Index.Fields) {
     if (isa<StringRecTy>(Field.RecType)) {
       OS << "      int Cmp" << Field.Name << " = StringRef(LHS." << Field.Name
          << ").compare(RHS." << Field.Name << ");\n";
       OS << "      if (Cmp" << Field.Name << " < 0) return true;\n";
       OS << "      if (Cmp" << Field.Name << " > 0) return false;\n";
+    } else if (Field.Enum) {
+      // Explicitly cast to unsigned, because the signedness of enums is
+      // compiler-dependent.
+      OS << "      if ((unsigned)LHS." << Field.Name
+         << " < (unsigned)RHS." << Field.Name << ")\n";
+      OS << "        return true;\n";
+      OS << "      if ((unsigned)LHS." << Field.Name
+         << " > (unsigned)RHS." << Field.Name << ")\n";
+      OS << "        return false;\n";
     } else {
       OS << "      if (LHS." << Field.Name << " < RHS." << Field.Name << ")\n";
       OS << "        return true;\n";
       OS << "      if (LHS." << Field.Name << " > RHS." << Field.Name << ")\n";
       OS << "        return false;\n";
     }
   }