Revert "[IRGen] Temporarily disable round-tripping debug types"

This reverts commit 13e7aff.

Author: lorentey

lib/Frontend/CompilerInvocation.cpp

@@ -2776,13 +2776,11 @@ static bool ParseIRGenArgs(IRGenOptions &Opts, ArgList &Args,
   if (Args.hasArg(OPT_no_clang_module_breadcrumbs))
     Opts.DisableClangModuleSkeletonCUs = true;
 
-  // FIXME(NCG): Temporarily force-disabled, it keeps tripping up on noncopyables (rdar://124564447)
-  // if (auto A = Args.getLastArg(OPT_enable_round_trip_debug_types,
-  //                              OPT_disable_round_trip_debug_types)) {
-  //   Opts.DisableRoundTripDebugTypes =
-  //       Args.hasArg(OPT_disable_round_trip_debug_types);
-  // }
-  Opts.DisableRoundTripDebugTypes = true;
+  if (auto A = Args.getLastArg(OPT_enable_round_trip_debug_types,
+                               OPT_disable_round_trip_debug_types)) {
+    Opts.DisableRoundTripDebugTypes =
+        Args.hasArg(OPT_disable_round_trip_debug_types);
+  }
 
   if (Args.hasArg(OPT_disable_debugger_shadow_copies))
     Opts.DisableDebuggerShadowCopies = true;