From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Bertalan <dani@danielbertalan.dev>
Date: Thu, 14 Apr 2022 10:17:13 +0200
Subject: [PATCH] [libc++] Add support for SerenityOS

This commit teaches libc++ about what features are available in our
LibC, namely:
* We do not have locale support, so no-op shims should be used in place
  of the C locale API.
* The number of errno constants defined by us is given by the value of
  the `ELAST` macro.
* Multithreading is implemented though the pthread library.
* Use libc++'s builtin character type table instead of the one provided
  by LibC as there's a lot of extra porting work to convince the rest of
  locale.cpp to use our character type table properly.
---
 libcxx/include/CMakeLists.txt               |  1 +
 libcxx/include/__config                     |  5 +++--
 libcxx/include/__locale                     |  2 ++
 libcxx/include/__support/serenity/xlocale.h | 24 +++++++++++++++++++++
 libcxx/include/locale                       |  2 +-
 libcxx/src/include/config_elast.h           |  2 ++
 6 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 libcxx/include/__support/serenity/xlocale.h

diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index a12aa1de1..075ebbe81 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -549,6 +549,7 @@ set(files
   __support/musl/xlocale.h
   __support/newlib/xlocale.h
   __support/openbsd/xlocale.h
+  __support/serenity/xlocale.h
   __support/solaris/floatingpoint.h
   __support/solaris/wchar.h
   __support/solaris/xlocale.h
diff --git a/libcxx/include/__config b/libcxx/include/__config
index 108153883..e4434809c 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -930,7 +930,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_END_NAMESPACE_STD
         defined(__sun__) ||                                                                                            \
         defined(__MVS__) ||                                                                                            \
         defined(_AIX) ||                                                                                               \
-        defined(__EMSCRIPTEN__)
+        defined(__EMSCRIPTEN__) ||                                                                                     \
+        defined(__serenity__)
 // clang-format on
 #      define _LIBCPP_HAS_THREAD_API_PTHREAD
 #    elif defined(__Fuchsia__)
@@ -1008,7 +1009,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_END_NAMESPACE_STD
 #  endif
 
 #  if defined(__BIONIC__) || defined(__NuttX__) || defined(__Fuchsia__) || defined(__wasi__) ||                        \
-      defined(_LIBCPP_HAS_MUSL_LIBC) || defined(__OpenBSD__)
+      defined(_LIBCPP_HAS_MUSL_LIBC) || defined(__OpenBSD__) || defined(__serenity__)
 #    define _LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE
 #  endif
 
diff --git a/libcxx/include/__locale b/libcxx/include/__locale
index e0ffa0ca0..33e994abe 100644
--- a/libcxx/include/__locale
+++ b/libcxx/include/__locale
@@ -44,6 +44,8 @@
 # include <__support/musl/xlocale.h>
 #elif defined(_LIBCPP_HAS_MUSL_LIBC)
 # include <__support/musl/xlocale.h>
+#elif defined(__serenity__)
+# include <__support/serenity/xlocale.h>
 #endif
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/__support/serenity/xlocale.h b/libcxx/include/__support/serenity/xlocale.h
new file mode 100644
index 000000000..0f939d2f6
--- /dev/null
+++ b/libcxx/include/__support/serenity/xlocale.h
@@ -0,0 +1,24 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_SUPPORT_SERENITY_XLOCALE_H
+#define _LIBCPP_SUPPORT_SERENITY_XLOCALE_H
+
+#if defined(__serenity__)
+
+#include <cstdlib>
+#include <clocale>
+#include <cwctype>
+#include <ctype.h>
+#include <__support/xlocale/__nop_locale_mgmt.h>
+#include <__support/xlocale/__posix_l_fallback.h>
+#include <__support/xlocale/__strtonum_fallback.h>
+
+#endif // __serenity__
+
+#endif
diff --git a/libcxx/include/locale b/libcxx/include/locale
index 874866f69..55632f101 100644
--- a/libcxx/include/locale
+++ b/libcxx/include/locale
@@ -216,7 +216,7 @@ template <class charT> class messages_byname;
 
 #if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 // Most unix variants have catopen.  These are the specific ones that don't.
-#  if !defined(__BIONIC__) && !defined(_NEWLIB_VERSION) && !defined(__EMSCRIPTEN__)
+#  if !defined(__BIONIC__) && !defined(_NEWLIB_VERSION) && !defined(__EMSCRIPTEN__) && !defined(__serenity__)
 #    define _LIBCPP_HAS_CATOPEN 1
 #    include <nl_types.h>
 #  endif
diff --git a/libcxx/src/include/config_elast.h b/libcxx/src/include/config_elast.h
index bef26ec50..fbb2899b1 100644
--- a/libcxx/src/include/config_elast.h
+++ b/libcxx/src/include/config_elast.h
@@ -35,6 +35,8 @@
 #define _LIBCPP_ELAST 4095
 #elif defined(__APPLE__)
 // No _LIBCPP_ELAST needed on Apple
+#elif defined(__serenity__)
+// No _LIBCPP_ELAST needed on SerenityOS
 #elif defined(__sun__)
 #define _LIBCPP_ELAST ESTALE
 #elif defined(__MVS__)