[CSApply] Use the choiceLocator, not locator when checking if a disjunction choice exists

Obviously we won't have a disjunction choice for the locator, it's only possible if the locator is extended with ImplicitlyUnwrappedDisjunctionChoice path element

Author: theblixguy

lib/Sema/CSApply.cpp

@@ -2269,21 +2269,20 @@ namespace {
       if (!choice.isImplicitlyUnwrappedValueOrReturnValue())
         return false;
 
-      // If we have an IUO function call and don't have a disjunction choice,
-      // then it means we didn't create a disjunction because the call was
-      // wrapped in parens (i.e. '(s.returnsAnIUO)()') and so there's no
-      // need to force unwrap.
-      if (!solution.DisjunctionChoices.count(
-              cs.getConstraintLocator(locator))) {
+      auto *choiceLocator = cs.getConstraintLocator(locator.withPathElement(
+          ConstraintLocator::ImplicitlyUnwrappedDisjunctionChoice));
+
+      // We won't have a disjunction choice if we have an IUO function call
+      // wrapped in parens (i.e. '(s.foo)()'), because we only create a
+      // single constraint to bind to an optional type. So, we can just return
+      // false here as there's no need to force unwrap.
+      if (!solution.DisjunctionChoices.count(choiceLocator)) {
         auto type = choice.getDecl()->getInterfaceType();
         assert((type && type->is<AnyFunctionType>()) &&
                "expected a function type");
         return false;
       }
 
-      auto *choiceLocator = cs.getConstraintLocator(locator.withPathElement(
-          ConstraintLocator::ImplicitlyUnwrappedDisjunctionChoice));
-
       return solution.getDisjunctionChoice(choiceLocator);
     }