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, 1 insertions, 1 deletions

diff --git a/Kernel/Devices/SB16.cpp b/Kernel/Devices/SB16.cpp
index befb4051d3..c0430c7259 100644
--- a/Kernel/Devices/SB16.cpp
+++ b/Kernel/Devices/SB16.cpp
@@ -227,7 +227,7 @@ void SB16::handle_irq(const RegisterState&)
 
 void SB16::wait_for_irq()
 {
-    m_irq_queue.wait_on(nullptr, "SB16");
+    m_irq_queue.wait_on({}, "SB16");
     disable_irq();
 }