Use TypeTraits in Alignment.h to make static assertions more readable

kernel/src/main.cpp

@@ -30,7 +30,7 @@ void heap_thread()
 {
     CPU::disable_interrupts();
     dump_heap_usage();
-    kdbgln("uses %lu vm pages", KernelVM::used() / ARCH_PAGE_SIZE);
+    kdbgln("Kernel uses %lu vm pages", KernelVM::used() / ARCH_PAGE_SIZE);
     while (true) kernel_sleep(UINT64_MAX);
 }
 

luna/include/luna/Alignment.h

@@ -1,9 +1,10 @@
 #pragma once
+#include <luna/TypeTraits.h>
 
 // Must ALWAYS be called with a power of two as alignment.
 template <usize alignment, typename T> constexpr T is_aligned(T value)
 {
-    static_assert((alignment & (alignment - 1)) == 0);
+    static_assert(IsPowerOfTwo<usize, alignment>);
     return (value % alignment == 0);
 }
 
@@ -14,7 +15,7 @@ static_assert(is_aligned<4096>(40960u));
 // Must ALWAYS be called with a power of two as alignment.
 template <usize alignment, typename T> constexpr T align_down(T value)
 {
-    static_assert((alignment & (alignment - 1)) == 0);
+    static_assert(IsPowerOfTwo<usize, alignment>);
     return value - value % alignment;
 }
 

luna/include/luna/LinkedList.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <luna/Option.h>
+#include <luna/TypeTraits.h>
 
 template <typename T> inline Option<T*> nonnull_or_error(T* ptr)
 {
@@ -57,6 +58,8 @@ template <typename T> class DoublyLinkedList
 {
     using Node = DoublyLinkedListNode<T>;
 
+    static_assert(IsBaseOf<DoublyLinkedListNode<T>, T>);
+
   public:
     void append(T* ptr)
     {

luna/include/luna/TypeTraits.h

@@ -0,0 +1,4 @@
+#pragma once
+
+template <typename Base, typename Derived> inline constexpr bool IsBaseOf = __is_base_of(Base, Derived);
+template <typename T, T value> inline constexpr bool IsPowerOfTwo = (value & (value - 1)) == 0;