AK: Simplify constructors and conversions from nullptr_t

Problem:
- Many constructors are defined as `{}` rather than using the ` =
  default` compiler-provided constructor.
- Some types provide an implicit conversion operator from `nullptr_t`
  instead of requiring the caller to default construct. This violates
  the C++ Core Guidelines suggestion to declare single-argument
  constructors explicit
  (https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit).

Solution:
- Change default constructors to use the compiler-provided default
  constructor.
- Remove implicit conversion operators from `nullptr_t` and change
  usage to enforce type consistency without conversion.

1 files changed, 2 insertions, 2 deletions

diff --git a/AK/SinglyLinkedListWithCount.h b/AK/SinglyLinkedListWithCount.h
index 8d3eb80427..a84762bae4 100644
--- a/AK/SinglyLinkedListWithCount.h
+++ b/AK/SinglyLinkedListWithCount.h
@@ -35,8 +35,8 @@ template<typename T>
 class SinglyLinkedListWithCount : private SinglyLinkedList<T> {
 
 public:
-    SinglyLinkedListWithCount() { }
-    ~SinglyLinkedListWithCount() { }
+    SinglyLinkedListWithCount() = default;
+    ~SinglyLinkedListWithCount() = default;
 
     using List = SinglyLinkedList<T>;