[LLDB] Fix conditional to also support AccessLevel::Open

[adrian-prantl]

[LLDB] Fix conditional to also support AccessLevel::Open
This fixes crashes in LLDB expression evaluation when calling virtual
Open functions.

rdar://147797657

and

Improve legibility of conditional
Commit bceb817 made the following edits:

   SILDeclRef method = i->getMember().getOverriddenVTableEntry();
   auto methodType = i->getType().castTo<SILFunctionType>();

+  AccessLevel methodAccess = method.getDecl()->getEffectiveAccess();
   auto *classDecl = cast<ClassDecl>(method.getDecl()->getDeclContext());
   bool shouldUseDispatchThunk = false;
-  if (IGM.hasResilientMetadata(classDecl, ResilienceExpansion::Maximal)) {
+  // Because typechecking for the debugger has more lax rules, check the access
+  // level of the getter to decide whether to use a dispatch thunk for the
+  // debugger.
+  bool shouldUseDispatchThunkIfInDebugger =
+      !classDecl->getASTContext().LangOpts.DebuggerSupport ||
+      methodAccess == AccessLevel::Public;
+  if (IGM.hasResilientMetadata(classDecl, ResilienceExpansion::Maximal) &&
+      shouldUseDispatchThunkIfInDebugger) {
     shouldUseDispatchThunk = true;
   } else if (IGM.getOptions().VirtualFunctionElimination) {
     // For VFE, use a thunk if the target class is in another module. This

This commit refactors the conditional that make it more obvious that
only the LLDB code path is meant to be affected.

[adrian-prantl]

@swift-ci test

[slavapestov]

The logic here is getting complex. Do you mind splitting off the entire computation of shouldUseDispatchThunk into a new top-level function?

[adrian-prantl]

The logic here is getting complex. Do you mind splitting off the entire computation of shouldUseDispatchThunk into a new top-level function?

Added a 3rd NFC commit on top.

[adrian-prantl]

@swift-ci test

[adrian-prantl]

@swift-ci test