MACAddress: AK::Array as member variable instead of C-array

Problem:
- C-style arrays do not automatically provide bounds checking and are
  less type safe overall.
- `__builtin_memcmp` is not a constant expression in the current gcc.

Solution:
- Change private m_data to be AK::Array.
- Eliminate constructor from C-style array.
- Change users of the C-style array constructor to use the default
  constructor.
- Change `operator==()` to be a hand-written comparison loop and let
  the optimizer figure out to use `memcmp`.

1 files changed, 16 insertions, 9 deletions

diff --git a/AK/Tests/TestMACAddress.cpp b/AK/Tests/TestMACAddress.cpp
index 3b6e4a0fac..cfc4455431 100644
--- a/AK/Tests/TestMACAddress.cpp
+++ b/AK/Tests/TestMACAddress.cpp
@@ -43,14 +43,6 @@ TEST_CASE(should_braces_construct)
     EXPECT(!sut.is_zero());
 }
 
-TEST_CASE(should_construct_from_c_array)
-{
-    constexpr u8 addr[6] = { 1, 2, 3, 4, 5, 6 };
-    constexpr MACAddress sut(addr);
-    static_assert(!sut.is_zero());
-    EXPECT(!sut.is_zero());
-}
-
 TEST_CASE(should_construct_from_6_octets)
 {
     constexpr MACAddress sut(1, 2, 3, 4, 5, 6);
@@ -58,7 +50,7 @@ TEST_CASE(should_construct_from_6_octets)
     EXPECT(!sut.is_zero());
 }
 
-TEST_CASE(should_provide_access_to_octet_by_index)
+TEST_CASE(should_provide_read_access_to_octet_by_index)
 {
     constexpr auto is_all_expected = [](auto& sut) {
         for (auto i = 0u; i < sizeof(MACAddress); ++i) {
@@ -78,6 +70,21 @@ TEST_CASE(should_provide_access_to_octet_by_index)
     }
 }
 
+TEST_CASE(should_provide_write_access_to_octet_by_index)
+{
+    constexpr auto sut = [] {
+        MACAddress m {};
+        for (auto i = 0u; i < sizeof(MACAddress); ++i) {
+            m[i] = i + 1;
+        }
+        return m;
+    }();
+
+    constexpr MACAddress expected(1, 2, 3, 4, 5, 6);
+
+    static_assert(expected == sut);
+}
+
 TEST_CASE(should_equality_compare)
 {
     constexpr MACAddress a(1, 2, 3, 4, 5, 6);