Add initial support for the MUSL C library.

Summary:
This patch adds the LIBCXX_LIBC_IS_MUSL cmake option to allow the
building of libcxx with the Musl C library. The option is necessary as
Musl does not provide any predefined macro in order to test for its
presence, like GLIBC. Most of the changes specify the correct path to
choose through the various #if/#else constructs in the locale code.

Depends on D13407.

Reviewers: mclow.lists, jroelofs, EricWF

Subscribers: jfb, tberghammer, danalbert, srhines, cfe-commits

Differential Revision: http://reviews.llvm.org/D13673

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@252457 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6cc36e0..8b60fb1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -121,6 +121,7 @@
 option(LIBCXX_ENABLE_MONOTONIC_CLOCK
   "Build libc++ with support for a monotonic clock.
    This option may only be set to OFF when LIBCXX_ENABLE_THREADS=OFF." ON)
+option(LIBCXX_HAS_MUSL_LIBC "Build libc++ with support for the Musl C library" OFF)
 
 # Misc options ----------------------------------------------------------------
 # FIXME: Turn -pedantic back ON. It is currently off because it warns
@@ -200,6 +201,11 @@
         LIBCXX_ENABLE_ABI_LINKER_SCRIPT")
 endif()
 
+if (LIBCXX_HAS_MUSL_LIBC AND NOT LIBCXX_INSTALL_SUPPORT_HEADERS)
+  message(FATAL_ERROR "LIBCXX_INSTALL_SUPPORT_HEADERS can not be turned off"
+                      "when building for Musl with LIBCXX_HAS_MUSL_LIBC.")
+endif()
+
 #===============================================================================
 # Configure System
 #===============================================================================
@@ -364,6 +370,8 @@
 config_define_if_not(LIBCXX_ENABLE_MONOTONIC_CLOCK _LIBCPP_HAS_NO_MONOTONIC_CLOCK)
 config_define_if_not(LIBCXX_ENABLE_THREAD_UNSAFE_C_FUNCTIONS _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS)
 
+config_define_if(LIBCXX_HAS_MUSL_LIBC _LIBCPP_HAS_MUSL_LIBC)
+
 if (LIBCXX_NEEDS_SITE_CONFIG)
   configure_file(
     include/__config_site.in
diff --git a/include/__config b/include/__config
index 7f6fbf0..795e084 100644
--- a/include/__config
+++ b/include/__config
@@ -386,14 +386,19 @@
 #elif defined(__ANDROID__)
 #define _LIBCPP_HAS_QUICK_EXIT
 #elif defined(__linux__)
-#include <features.h>
+#if !defined(_LIBCPP_HAS_MUSL_LIBC)
+# include <features.h>
 #if __GLIBC_PREREQ(2, 15)
 #define _LIBCPP_HAS_QUICK_EXIT
 #endif
 #if __GLIBC_PREREQ(2, 17)
 #define _LIBCPP_HAS_C11_FEATURES
 #endif
+#else // defined(_LIBCPP_HAS_MUSL_LIBC)
+#define _LIBCPP_HAS_QUICK_EXIT
+#define _LIBCPP_HAS_C11_FEATURES
 #endif
+#endif // __linux__
 #endif
 
 #if (__has_feature(cxx_noexcept))
diff --git a/include/__config_site.in b/include/__config_site.in
index 7a1d739..ec64485 100644
--- a/include/__config_site.in
+++ b/include/__config_site.in
@@ -18,5 +18,6 @@
 #cmakedefine _LIBCPP_HAS_NO_THREADS
 #cmakedefine _LIBCPP_HAS_NO_MONOTONIC_CLOCK
 #cmakedefine _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
+#cmakedefine _LIBCPP_HAS_MUSL_LIBC
 
-#endif
+#endif // _LIBCPP_CONFIG_SITE
diff --git a/include/__locale b/include/__locale
index 1989558..e525053 100644
--- a/include/__locale
+++ b/include/__locale
@@ -37,6 +37,8 @@
 #elif (defined(__GLIBC__) || defined(__APPLE__)      || defined(__FreeBSD__) \
     || defined(__EMSCRIPTEN__) || defined(__IBMCPP__))
 # include <xlocale.h>
+#elif defined(_LIBCPP_HAS_MUSL_LIBC)
+# include <support/musl/xlocale.h>
 #endif // __GLIBC__ || __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -329,7 +331,7 @@
 class _LIBCPP_TYPE_VIS ctype_base
 {
 public:
-#ifdef __GLIBC__
+#if defined(__GLIBC__)
     typedef unsigned short mask;
     static const mask space  = _ISspace;
     static const mask print  = _ISprint;
@@ -359,7 +361,7 @@
     typedef __uint32_t mask;
 # elif defined(__FreeBSD__)
     typedef unsigned long mask;
-# elif defined(__EMSCRIPTEN__) ||  defined(__NetBSD__)
+# elif defined(__EMSCRIPTEN__) || defined(__NetBSD__) || defined(_LIBCPP_HAS_MUSL_LIBC)
     typedef unsigned short mask;
 # endif
     static const mask space  = _CTYPE_S;
@@ -406,7 +408,11 @@
 # define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_ALPHA
 # define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_XDIGIT
 #else
+#if defined(_LIBCPP_HAS_MUSL_LIBC)
+    typedef unsigned short mask;
+#else
     typedef unsigned long mask;
+#endif
     static const mask space  = 1<<0;
     static const mask print  = 1<<1;
     static const mask cntrl  = 1<<2;
@@ -628,7 +634,7 @@
 #endif
     _LIBCPP_ALWAYS_INLINE const mask* table() const  _NOEXCEPT {return __tab_;}
     static const mask* classic_table()  _NOEXCEPT;
-#if defined(__GLIBC__) || defined(__EMSCRIPTEN__)
+#if defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(_LIBCPP_HAS_MUSL_LIBC)
     static const int* __classic_upper_table() _NOEXCEPT;
     static const int* __classic_lower_table() _NOEXCEPT;
 #endif
diff --git a/include/support/musl/xlocale.h b/include/support/musl/xlocale.h
new file mode 100644
index 0000000..3e31c99
--- /dev/null
+++ b/include/support/musl/xlocale.h
@@ -0,0 +1,58 @@
+// -*- C++ -*-
+//===------------------- support/musl/xlocale.h ------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// This adds support for the extended locale functions that are currently
+// missing from the Musl C library.
+//
+// This only works when the specified locale is "C" or "POSIX", but that's
+// about as good as we can do without implementing full xlocale support
+// in Musl.
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_SUPPORT_MUSL_XLOCALE_H
+#define _LIBCPP_SUPPORT_MUSL_XLOCALE_H
+
+#include <cstdlib>
+#include <cwchar>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static inline long long strtoll_l(const char *nptr, char **endptr, int base,
+                                  locale_t) {
+  return strtoll(nptr, endptr, base);
+}
+
+static inline unsigned long long strtoull_l(const char *nptr, char **endptr,
+                                            int base, locale_t) {
+  return strtoull(nptr, endptr, base);
+}
+
+static inline long long wcstoll_l(const wchar_t *nptr, wchar_t **endptr,
+                                  int base, locale_t) {
+  return wcstoll(nptr, endptr, base);
+}
+
+static inline unsigned long long wcstoull_l(const wchar_t *nptr,
+                                            wchar_t **endptr, int base,
+                                            locale_t) {
+  return wcstoull(nptr, endptr, base);
+}
+
+static inline long double wcstold_l(const wchar_t *nptr, wchar_t **endptr,
+                                    locale_t) {
+  return wcstold(nptr, endptr);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _LIBCPP_SUPPORT_MUSL_XLOCALE_H
diff --git a/src/locale.cpp b/src/locale.cpp
index bdc73e1..11c266c 100644
--- a/src/locale.cpp
+++ b/src/locale.cpp
@@ -812,7 +812,8 @@
 {
 #ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
     return isascii(c) ? _DefaultRuneLocale.__mapupper[c] : c;
-#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(__NetBSD__)
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || \
+      defined(__NetBSD__) || defined(_LIBCPP_HAS_MUSL_LIBC)
     return isascii(c) ? ctype<char>::__classic_upper_table()[c] : c;
 #else
     return (isascii(c) && iswlower_l(c, _LIBCPP_GET_C_LOCALE)) ? c-L'a'+L'A' : c;
@@ -825,7 +826,8 @@
     for (; low != high; ++low)
 #ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
         *low = isascii(*low) ? _DefaultRuneLocale.__mapupper[*low] : *low;
-#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(__NetBSD__)
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || \
+      defined(__NetBSD__) || defined(_LIBCPP_HAS_MUSL_LIBC)
         *low = isascii(*low) ? ctype<char>::__classic_upper_table()[*low]
                              : *low;
 #else
@@ -839,7 +841,8 @@
 {
 #ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
     return isascii(c) ? _DefaultRuneLocale.__maplower[c] : c;
-#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(__NetBSD__)
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || \
+      defined(__NetBSD__) || defined(_LIBCPP_HAS_MUSL_LIBC)
     return isascii(c) ? ctype<char>::__classic_lower_table()[c] : c;
 #else
     return (isascii(c) && isupper_l(c, _LIBCPP_GET_C_LOCALE)) ? c-L'A'+'a' : c;
@@ -852,7 +855,8 @@
     for (; low != high; ++low)
 #ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
         *low = isascii(*low) ? _DefaultRuneLocale.__maplower[*low] : *low;
-#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(__NetBSD__)
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || \
+      defined(__NetBSD__) || defined(_LIBCPP_HAS_MUSL_LIBC)
         *low = isascii(*low) ? ctype<char>::__classic_lower_table()[*low]
                              : *low;
 #else
@@ -921,8 +925,8 @@
       static_cast<char>(_DefaultRuneLocale.__mapupper[static_cast<ptrdiff_t>(c)]) : c;
 #elif defined(__NetBSD__)
     return static_cast<char>(__classic_upper_table()[static_cast<unsigned char>(c)]);
-#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__)
-    return isascii(c) ? 
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(_LIBCPP_HAS_MUSL_LIBC)
+    return isascii(c) ?
       static_cast<char>(__classic_upper_table()[static_cast<unsigned char>(c)]) : c;
 #else
     return (isascii(c) && islower_l(c, _LIBCPP_GET_C_LOCALE)) ? c-'a'+'A' : c;
@@ -938,7 +942,7 @@
           static_cast<char>(_DefaultRuneLocale.__mapupper[static_cast<ptrdiff_t>(*low)]) : *low;
 #elif defined(__NetBSD__)
         *low = static_cast<char>(__classic_upper_table()[static_cast<unsigned char>(*low)]);
-#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__)
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(_LIBCPP_HAS_MUSL_LIBC)
         *low = isascii(*low) ?
           static_cast<char>(__classic_upper_table()[static_cast<size_t>(*low)]) : *low;
 #else
@@ -955,7 +959,7 @@
       static_cast<char>(_DefaultRuneLocale.__maplower[static_cast<ptrdiff_t>(c)]) : c;
 #elif defined(__NetBSD__)
     return static_cast<char>(__classic_lower_table()[static_cast<unsigned char>(c)]);
-#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(__NetBSD__)
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(_LIBCPP_HAS_MUSL_LIBC)
     return isascii(c) ?
       static_cast<char>(__classic_lower_table()[static_cast<size_t>(c)]) : c;
 #else
@@ -971,7 +975,7 @@
         *low = isascii(*low) ? static_cast<char>(_DefaultRuneLocale.__maplower[static_cast<ptrdiff_t>(*low)]) : *low;
 #elif defined(__NetBSD__)
         *low = static_cast<char>(__classic_lower_table()[static_cast<unsigned char>(*low)]);
-#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__)
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || defined(_LIBCPP_HAS_MUSL_LIBC)
         *low = isascii(*low) ? static_cast<char>(__classic_lower_table()[static_cast<size_t>(*low)]) : *low;
 #else
         *low = (isascii(*low) && isupper_l(*low, _LIBCPP_GET_C_LOCALE)) ? *low-'A'+'a' : *low;
@@ -1012,7 +1016,7 @@
     return low;
 }
 
-#ifdef __EMSCRIPTEN__
+#if defined(__EMSCRIPTEN__) || defined(_LIBCPP_HAS_MUSL_LIBC)
 extern "C" const unsigned short ** __ctype_b_loc();
 extern "C" const int ** __ctype_tolower_loc();
 extern "C" const int ** __ctype_toupper_loc();
@@ -1114,7 +1118,7 @@
     return _ctype+1; // internal ctype mask table defined in msvcrt.dll
 // This is assumed to be safe, which is a nonsense assumption because we're
 // going to end up dereferencing it later...
-#elif defined(__EMSCRIPTEN__)
+#elif defined(__EMSCRIPTEN__) || defined(_LIBCPP_HAS_MUSL_LIBC)
     return *__ctype_b_loc();
 #elif defined(_NEWLIB_VERSION)
     // Newlib has a 257-entry table in ctype_.c, where (char)0 starts at [1].
@@ -1157,7 +1161,7 @@
     return _C_toupper_tab_ + 1;
 }
 
-#elif defined(__EMSCRIPTEN__)
+#elif defined(__EMSCRIPTEN__) || defined(_LIBCPP_HAS_MUSL_LIBC)
 const int*
 ctype<char>::__classic_lower_table() _NOEXCEPT
 {
@@ -1169,7 +1173,7 @@
 {
     return *__ctype_toupper_loc();
 }
-#endif // __GLIBC__ || __EMSCRIPTEN__ || __NETBSD__
+#endif // __GLIBC__ || __NETBSD__ || __EMSCRIPTEN__ || defined(_LIBCPP_HAS_MUSL_LIBC)
 
 // template <> class ctype_byname<char>