From a650c74b27cae619eac102b8bdcbae642af1eaf1 Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gbeutner@serenityos.org>
Date: Wed, 12 Oct 2022 22:00:21 +0200
Subject: [PATCH] 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                  | 12 ++++++++++++
 CMakeLists.txt                           |  5 +++++
 Tests/LibC/TestWchar.cpp                 | 14 +++++++-------
 Userland/Libraries/LibRegex/RegexMatch.h |  8 +++++---
 4 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/AK/StdLibExtraDetails.h b/AK/StdLibExtraDetails.h
index 3746f1c280a..a970cfd2bb9 100644
--- a/AK/StdLibExtraDetails.h
+++ b/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;
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0344af4abe8..8df01f31d6d 100644
--- a/CMakeLists.txt
+++ b/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(.)
diff --git a/Tests/LibC/TestWchar.cpp b/Tests/LibC/TestWchar.cpp
index 86a3e61692f..db445e485e9 100644
--- a/Tests/LibC/TestWchar.cpp
+++ b/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);
diff --git a/Userland/Libraries/LibRegex/RegexMatch.h b/Userland/Libraries/LibRegex/RegexMatch.h
index a15cabb744f..04f2e0483bd 100644
--- a/Userland/Libraries/LibRegex/RegexMatch.h
+++ b/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); },