`std::result_of` was removed in C++20, but is still used in the Swift headers. We can't
remove it from there before prebuilding, as that is still done with C++14, but we can
replace it with `std::invoke_result` for compiling the extractor.

diff --git a/include/swift/Basic/RelativePointer.h b/include/swift/Basic/RelativePointer.h
index 73f91262afa..bdaa304c804 100644
--- a/include/swift/Basic/RelativePointer.h
+++ b/include/swift/Basic/RelativePointer.h
@@ -551,7 +551,7 @@ public:
   }

   template <typename... ArgTy>
-  typename std::result_of<T *(ArgTy...)>::type operator()(ArgTy... arg) const {
+  typename std::invoke_result<T*, ArgTy...>::type operator()(ArgTy... arg) const {
 #if SWIFT_PTRAUTH
     void *ptr = this->super::getWithoutCast();
     return reinterpret_cast<T *>(ptrauth_sign_unauthenticated(
diff --git a/include/swift/Basic/STLExtras.h b/include/swift/Basic/STLExtras.h
index 7fa3d0c8890..6bc891a9b63 100644
--- a/include/swift/Basic/STLExtras.h
+++ b/include/swift/Basic/STLExtras.h
@@ -405,7 +405,7 @@ class OptionalTransformIterator {
       typename std::iterator_traits<Iterator>::reference;

   using ResultReference =
-      typename std::result_of<OptionalTransform(UnderlyingReference)>::type;
+      typename std::invoke_result<OptionalTransform, UnderlyingReference>::type;

 public:
   /// Used to indicate when the current iterator has already been