Sema: Make wonky logic explicit in diagnoseImplicitSelfUseInClosure()

We walk up the DeclContext hierarchy looking for closures, but they might
not have had their types set yet because they're currently being type
checked.

Author: slavapestov

lib/Sema/MiscDiagnostics.cpp

@@ -1823,9 +1823,10 @@ static void diagnoseImplicitSelfUseInClosure(const Expr *E,
 
       // If the closure's type was inferred to be noescape, then it doesn't
       // need qualification.
-      if (AnyFunctionRef(const_cast<AbstractClosureExpr *>(CE))
-               .isKnownNoEscape())
-        return false;
+      if (auto funcTy = CE->getType()->getAs<FunctionType>()) {
+        if (funcTy->isNoEscape())
+          return false;
+      }
 
       if (auto autoclosure = dyn_cast<AutoClosureExpr>(CE)) {
         if (autoclosure->getThunkKind() == AutoClosureExpr::Kind::AsyncLet)
@@ -2094,9 +2095,11 @@ static void diagnoseImplicitSelfUseInClosure(const Expr *E,
   AbstractClosureExpr *ACE = nullptr;
   if (DC->isLocalContext()) {
     while (DC->getParent()->isLocalContext() && !ACE) {
+      // FIXME: This is happening too early, because closure->getType() isn't set.
       if (auto *closure = dyn_cast<AbstractClosureExpr>(DC))
-        if (DiagnoseWalker::isClosureRequiringSelfQualification(closure, ctx))
-          ACE = const_cast<AbstractClosureExpr *>(closure);
+        if (closure->getType())
+          if (DiagnoseWalker::isClosureRequiringSelfQualification(closure, ctx))
+            ACE = const_cast<AbstractClosureExpr *>(closure);
       DC = DC->getParent();
     }
   }