fix ctad warning in llvm

1 files changed, 8 insertions, 1 deletions

diff --git a/include/gsl/pointers b/include/gsl/pointers
index 7373826..2520f9e 100644
--- a/include/gsl/pointers
+++ b/include/gsl/pointers
@@ -100,7 +100,7 @@ public:
 
     constexpr operator T() const { return get(); }
     constexpr T operator->() const { return get(); }
-    constexpr decltype(auto) operator*() const { return *get(); } 
+    constexpr decltype(auto) operator*() const { return *get(); }
 
     // prevents compilation when someone attempts to assign a null pointer constant
     not_null(std::nullptr_t) = delete;
@@ -119,6 +119,13 @@ private:
     T ptr_;
 };
 
+#if (defined(__cplusplus) && (__cplusplus >= 201703L))
+// deduction guide to prevent the ctad-maybe-unsupported warning
+template <class T>
+not_null(T ptr) -> not_null<T>;
+
+#endif (defined(__cplusplus) && (__cplusplus >= 201703L))
+
 template <class T>
 auto make_not_null(T&& t) {
     return not_null<std::remove_cv_t<std::remove_reference_t<T>>>{std::forward<T>(t)};