AK: Add hash traits for floating-point primitives

This allows us to use float and double as hash keys.

AK/Traits.h

@@ -40,6 +40,20 @@ requires(IsIntegral<T>) struct Traits<T> : public GenericTraits<T> {
     }
 };
 
+#ifndef KERNEL
+template<typename T>
+requires(IsFloatingPoint<T>) struct Traits<T> : public GenericTraits<T> {
+    static constexpr bool is_trivial() { return true; }
+    static constexpr unsigned hash(T value)
+    {
+        if constexpr (sizeof(T) < 8)
+            return int_hash(bit_cast<u32>(value));
+        else
+            return u64_hash(bit_cast<u64>(value));
+    }
+};
+#endif
+
 template<typename T>
 requires(IsPointer<T> && !Detail::IsPointerOfType<char, T>) struct Traits<T> : public GenericTraits<T> {
     static unsigned hash(T p) { return ptr_hash((FlatPtr)p); }

Tests/AK/TestHashTable.cpp

@@ -256,6 +256,30 @@ TEST_CASE(non_trivial_type_table)
     EXPECT_EQ(table.remove_all_matching([&](auto&) { return true; }), false);
 }
 
+TEST_CASE(floats)
+{
+    HashTable<float> table;
+    table.set(0);
+    table.set(1.0f);
+    table.set(2.0f);
+    EXPECT_EQ(table.size(), 3u);
+    EXPECT(table.contains(0));
+    EXPECT(table.contains(1.0f));
+    EXPECT(table.contains(2.0f));
+}
+
+TEST_CASE(doubles)
+{
+    HashTable<double> table;
+    table.set(0);
+    table.set(1.0);
+    table.set(2.0);
+    EXPECT_EQ(table.size(), 3u);
+    EXPECT(table.contains(0));
+    EXPECT(table.contains(1.0));
+    EXPECT(table.contains(2.0));
+}
+
 // Inserting and removing a bunch of elements will "thrash" the table, leading to a lot of "deleted" markers.
 BENCHMARK_CASE(benchmark_thrashing)
 {