AK+Toolchain: Make char and wchar_t behave on AARCH64

By default char and wchar_t are unsigned on AARCH64. This fixes a
bunch of related compiler errors.

AK/StdLibExtraDetails.h

@@ -274,6 +274,12 @@ template<>
 struct __MakeUnsigned<bool> {
     using Type = bool;
 };
+#ifdef AK_ARCH_AARCH64
+template<>
+struct __MakeUnsigned<wchar_t> {
+    using Type = wchar_t;
+};
+#endif
 
 template<typename T>
 using MakeUnsigned = typename __MakeUnsigned<T>::Type;
@@ -326,6 +332,12 @@ template<>
 struct __MakeSigned<char> {
     using Type = char;
 };
+#ifdef AK_ARCH_AARCH64
+template<>
+struct __MakeSigned<wchar_t> {
+    using Type = void;
+};
+#endif
 
 template<typename T>
 using MakeSigned = typename __MakeSigned<T>::Type;

CMakeLists.txt

@@ -182,6 +182,11 @@ if (ENABLE_COMPILETIME_FORMAT_CHECK)
     add_compile_definitions(ENABLE_COMPILETIME_FORMAT_CHECK)
 endif()
 
+if("${SERENITY_ARCH}" STREQUAL "aarch64")
+    # FIXME: re-enable this warning
+    add_compile_options(-Wno-type-limits)
+endif()
+
 add_link_options(-Wno-unused-command-line-argument)
 
 include_directories(.)

Tests/LibC/TestWchar.cpp

@@ -239,17 +239,17 @@ TEST_CASE(mbrtowc)
     // Ensure that we can parse normal ASCII characters.
     ret = mbrtowc(&wc, "Hello", 5, &state);
     EXPECT_EQ(ret, 1ul);
-    EXPECT_EQ(wc, 'H');
+    EXPECT_EQ(wc, static_cast<wchar_t>('H'));
 
     // Try two three-byte codepoints (™™), only one of which should be consumed.
     ret = mbrtowc(&wc, "\xe2\x84\xa2\xe2\x84\xa2", 6, &state);
     EXPECT_EQ(ret, 3ul);
-    EXPECT_EQ(wc, 0x2122);
+    EXPECT_EQ(wc, static_cast<wchar_t>(0x2122));
 
     // Try a null character, which should return 0 and reset the state to the initial state.
     ret = mbrtowc(&wc, "\x00\x00", 2, &state);
     EXPECT_EQ(ret, 0ul);
-    EXPECT_EQ(wc, 0);
+    EXPECT_EQ(wc, static_cast<wchar_t>(0));
     EXPECT_NE(mbsinit(&state), 0);
 
     // Try an incomplete multibyte character.
@@ -262,7 +262,7 @@ TEST_CASE(mbrtowc)
     // Finish the previous multibyte character.
     ret = mbrtowc(&wc, "\xa2", 1, &state);
     EXPECT_EQ(ret, 1ul);
-    EXPECT_EQ(wc, 0x2122);
+    EXPECT_EQ(wc, static_cast<wchar_t>(0x2122));
 
     // Try an invalid multibyte sequence.
     // Reset the state afterwards because the effects are undefined.
@@ -550,17 +550,17 @@ TEST_CASE(mbtowc)
     // Ensure that we can parse normal ASCII characters.
     ret = mbtowc(&wc, "Hello", 5);
     EXPECT_EQ(ret, 1);
-    EXPECT_EQ(wc, 'H');
+    EXPECT_EQ(wc, static_cast<wchar_t>('H'));
 
     // Try two three-byte codepoints (™™), only one of which should be consumed.
     ret = mbtowc(&wc, "\xe2\x84\xa2\xe2\x84\xa2", 6);
     EXPECT_EQ(ret, 3);
-    EXPECT_EQ(wc, 0x2122);
+    EXPECT_EQ(wc, static_cast<wchar_t>(0x2122));
 
     // Try a null character, which should return 0.
     ret = mbtowc(&wc, "\x00\x00", 2);
     EXPECT_EQ(ret, 0);
-    EXPECT_EQ(wc, 0);
+    EXPECT_EQ(wc, static_cast<wchar_t>(0));
 
     // Try an incomplete multibyte character.
     ret = mbtowc(&wc, "\xe2\x84", 2);

Userland/Libraries/LibRegex/RegexMatch.h

@@ -270,9 +270,11 @@ public:
         return m_view.visit(
             [&](StringView view) -> u32 {
                 auto ch = view[index];
-                if (ch < 0)
-                    return 256u + ch;
-                return ch;
+                if constexpr (IsSigned<char>) {
+                    if (ch < 0)
+                        return 256u + ch;
+                    return ch;
+                }
             },
             [&](Utf32View const& view) -> u32 { return view[index]; },
             [&](Utf16View const& view) -> u32 { return view.code_point_at(index); },