Add assertions to ensure memcpySpan and memsetSpan are used on trivia…

…lly copyable spans

https://bugs.webkit.org/show_bug.cgi?id=264619

Reviewed by Darin Adler.

Bad things are likely to happen if used on objects with custom
constructors or destructors or assignment operators, because they won't
be executed. Add safety checks for this.

* Source/WTF/wtf/Algorithms.h:
(WTF::memcpySpan):
(WTF::memsetSpan):

Canonical link: https://commits.webkit.org/270796@main

Source/WTF/wtf/Algorithms.h

@@ -27,6 +27,7 @@
 
 #include <cstring>
 #include <span>
+#include <type_traits>
 #include <wtf/Assertions.h>
 
 namespace WTF {
@@ -71,12 +72,15 @@ void memcpySpan(std::span<T> destination, std::span<U> source)
 {
     RELEASE_ASSERT(destination.size() == source.size());
     static_assert(sizeof(T) == sizeof(U));
+    static_assert(std::is_trivially_copyable_v<T>);
+    static_assert(std::is_trivially_copyable_v<U>);
     memcpy(destination.data(), source.data(), destination.size() * sizeof(T));
 }
 
 template<typename T>
 void memsetSpan(std::span<T> destination, uint8_t byte)
 {
+    static_assert(std::is_trivially_copyable_v<T>);
     memset(destination.data(), byte, destination.size() * sizeof(T));
 }