[libc++] Remove MSVC code

[philnik]

Summary

It's been one and a half months now and nobody said anything, so I guess this code can be removed.

[Mordante]

Has this diagnostic ever been in a released version of libc++?
IMO having nobody noticing it for only 6 weeks seems too short to me.

[philnik]

In D132943#3758775, @Mordante wrote:

Has this diagnostic ever been in a released version of libc++?
IMO having nobody noticing it for only 6 weeks seems too short to me.

Yes, it's in LLVM 15. Though I would expect anybody who has a working configuration to track ToT fairly closely, since I think it would be quite an effort to update such a configuration only every release. How long do you think we should wait before removing the code?

[Mordante]

In D132943#3758779, @philnik wrote:

In D132943#3758775, @Mordante wrote:

Has this diagnostic ever been in a released version of libc++?
IMO having nobody noticing it for only 6 weeks seems too short to me.

Yes, it's in LLVM 15. Though I would expect anybody who has a working configuration to track ToT fairly closely, since I think it would be quite an effort to update such a configuration only every release. How long do you think we should wait before removing the code?

LLVM 15 hasn't been released yet. I think doing it a few months after the release would be better. Or is there an urgent reason for the removal?

[philnik]

In D132943#3759178, @Mordante wrote:

In D132943#3758779, @philnik wrote:

In D132943#3758775, @Mordante wrote:

Has this diagnostic ever been in a released version of libc++?
IMO having nobody noticing it for only 6 weeks seems too short to me.

Yes, it's in LLVM 15. Though I would expect anybody who has a working configuration to track ToT fairly closely, since I think it would be quite an effort to update such a configuration only every release. How long do you think we should wait before removing the code?

LLVM 15 hasn't been released yet. I think doing it a few months after the release would be better. Or is there an urgent reason for the removal?

Right, the release stuff takes a few months. I'll wait a bit longer.

[ldionne]

Just to be clear -- I'm in favour of this, however I want to make sure that anyone reading this doesn't get the wrong impression. We *are* interested in supporting MSVC (although there is no current effort to do that AFAICT). This removal is not a statement of "not wanting to support MSVC", it's simply removing code that is dead, has been dead for we don't know how long, and likely doesn't work.

If we ever make an effort to port to MSVC (which I think would be interesting and maybe not even that difficult since we already support Windows), we should do it properly with CI to make sure it doesn't rot. Let's wait another week and ship this. If anything, we can always revert.

libcxx/include/CMakeLists.txt

set(files
   __support/ibm/nanosleep.h
   __support/ibm/xlocale.h
   __support/musl/xlocale.h
   __support/newlib/xlocale.h
   __support/openbsd/xlocale.h
   __support/solaris/floatingpoint.h
   __support/solaris/wchar.h
   __support/solaris/xlocale.h
-  __support/win32/limits_msvc_win32.h
   __support/win32/locale_win32.h
   __support/xlocale/__nop_locale_mgmt.h
   __support/xlocale/__posix_l_fallback.h
   __support/xlocale/__strtonum_fallback.h
   __thread/poll_with_backoff.h
   __thread/timed_backoff_policy.h
   __threading_support
   __tree

libcxx/include/__bits

 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#ifndef _LIBCPP_COMPILER_MSVC
-
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
 int __libcpp_ctz(unsigned __x)           _NOEXCEPT { return __builtin_ctz(__x); }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
 int __libcpp_ctz(unsigned long __x)      _NOEXCEPT { return __builtin_ctzl(__x); }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
 int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }

 int __libcpp_popcount(unsigned __x)           _NOEXCEPT { return __builtin_popcount(__x); }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
 int __libcpp_popcount(unsigned long __x)      _NOEXCEPT { return __builtin_popcountl(__x); }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
 int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); }
 
-#else  // _LIBCPP_COMPILER_MSVC
-
-// Precondition:  __x != 0
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_ctz(unsigned __x) {
-  static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
-  static_assert(sizeof(unsigned long) == 4, "");
-  unsigned long __where;
-  if (_BitScanForward(&__where, __x))
-    return static_cast<int>(__where);
-  return 32;
-}
-
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_ctz(unsigned long __x) {
-    static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
-    return __ctz(static_cast<unsigned>(__x));
-}
-
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_ctz(unsigned long long __x) {
-    unsigned long __where;
-#if defined(_LIBCPP_HAS_BITSCAN64)
-  if (_BitScanForward64(&__where, __x))
-    return static_cast<int>(__where);
-#else
-  // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
-  if (_BitScanForward(&__where, static_cast<unsigned long>(__x)))
-    return static_cast<int>(__where);
-  if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32)))
-    return static_cast<int>(__where + 32);
-#endif
-  return 64;
-}
-
-// Precondition:  __x != 0
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_clz(unsigned __x) {
-  static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
-  static_assert(sizeof(unsigned long) == 4, "");
-  unsigned long __where;
-  if (_BitScanReverse(&__where, __x))
-    return static_cast<int>(31 - __where);
-  return 32; // Undefined Behavior.
-}
-
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_clz(unsigned long __x) {
-    static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
-    return __libcpp_clz(static_cast<unsigned>(__x));
-}
-
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_clz(unsigned long long __x) {
-  unsigned long __where;
-#if defined(_LIBCPP_HAS_BITSCAN64)
-  if (_BitScanReverse64(&__where, __x))
-    return static_cast<int>(63 - __where);
-#else
-  // Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls.
-  if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32)))
-    return static_cast<int>(63 - (__where + 32));
-  if (_BitScanReverse(&__where, static_cast<unsigned long>(__x)))
-    return static_cast<int>(63 - __where);
-#endif
-  return 64; // Undefined Behavior.
-}
-
-inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned __x) {
-  static_assert(sizeof(unsigned) == 4, "");
-  return __popcnt(__x);
-}
-
-inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long __x) {
-  static_assert(sizeof(unsigned long) == 4, "");
-  return __popcnt(__x);
-}
-
-inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long long __x) {
-  static_assert(sizeof(unsigned long long) == 8, "");
-  return __popcnt64(__x);
-}
-
-#endif // _LIBCPP_COMPILER_MSVC
-
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___BITS

libcxx/include/__config

 #  if defined(__apple_build_version__)
 #    define _LIBCPP_COMPILER_CLANG_BASED
 #    define _LIBCPP_APPLE_CLANG_VER (__apple_build_version__ / 10000)
 #  elif defined(__clang__)
 #    define _LIBCPP_COMPILER_CLANG_BASED
 #    define _LIBCPP_CLANG_VER (__clang_major__ * 100 + __clang_minor__)
 #  elif defined(__GNUC__)
 #    define _LIBCPP_COMPILER_GCC
-#  elif defined(_MSC_VER)
-#    define _LIBCPP_COMPILER_MSVC
 #  endif
 
 #  if !defined(_LIBCPP_COMPILER_CLANG_BASED) && __cplusplus < 201103L
 #    error "libc++ only supports C++03 with Clang-based compilers. Please enable C++11"
 #  endif
 
-#  ifdef _LIBCPP_COMPILER_MSVC
-#    error If you successfully use libc++ with MSVC please tell the libc++ developers and consider upstreaming your \
-changes. We are not aware of anybody using this configuration and know that at least some code is currently broken. \
-If there are users of this configuration we are happy to provide support.
-#  endif
-
 // FIXME: ABI detection should be done via compiler builtin macros. This
 // is just a placeholder until Clang implements such macros. For now assume
 // that Windows compilers pretending to be MSVC++ target the Microsoft ABI,
 // and allow the user to explicitly specify the ABI to handle cases where this
 // heuristic falls short.
 #  if defined(_LIBCPP_ABI_FORCE_ITANIUM) && defined(_LIBCPP_ABI_FORCE_MICROSOFT)
 #    error "Only one of _LIBCPP_ABI_FORCE_ITANIUM and _LIBCPP_ABI_FORCE_MICROSOFT can be defined"
 #  elif defined(_LIBCPP_ABI_FORCE_ITANIUM)

 #    if !defined(__SANITIZE_ADDRESS__)
 #      define _LIBCPP_HAS_NO_ASAN
 #    endif
 
 #    define _LIBCPP_ALWAYS_INLINE __attribute__((__always_inline__))
 
 #    define _LIBCPP_DISABLE_EXTENSION_WARNING __extension__
 
-#  elif defined(_LIBCPP_COMPILER_MSVC)
-
-#    define _LIBCPP_WARNING(x) __pragma(message(__FILE__ "(" _LIBCPP_TOSTRING(__LINE__) ") : warning note: " x))
-
-#    if _MSC_VER < 1900
-#      error "MSVC versions prior to Visual Studio 2015 are not supported"
-#    endif
-
-#    define _LIBCPP_NORETURN __declspec(noreturn)
-
-#    define _LIBCPP_WEAK
-
-#    define _LIBCPP_HAS_NO_ASAN
-
-#    define _LIBCPP_ALWAYS_INLINE __forceinline
-
-#    define _LIBCPP_HAS_NO_VECTOR_EXTENSION
-
-#    define _LIBCPP_DISABLE_EXTENSION_WARNING
-
-#  endif // _LIBCPP_COMPILER_[CLANG|GCC|MSVC]
+#  endif // _LIBCPP_COMPILER_[CLANG|GCC]
 
 #  if defined(_LIBCPP_OBJECT_FORMAT_COFF)
 
 #    ifdef _DLL
 #      define _LIBCPP_CRT_FUNC __declspec(dllimport)
 #    else
 #      define _LIBCPP_CRT_FUNC
 #    endif

 // disabling it without having to resort to #if-#endif, which has a larger
 // impact on readability.
 #  if defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
 #    define _LIBCPP_IF_WIDE_CHARACTERS(...)
 #  else
 #    define _LIBCPP_IF_WIDE_CHARACTERS(...) __VA_ARGS__
 #  endif
 
-#  if defined(_LIBCPP_ABI_MICROSOFT) && (defined(_LIBCPP_COMPILER_MSVC) || __has_declspec_attribute(empty_bases))
+#  if defined(_LIBCPP_ABI_MICROSOFT) && __has_declspec_attribute(empty_bases)
 #    define _LIBCPP_DECLSPEC_EMPTY_BASES __declspec(empty_bases)
 #  else
 #    define _LIBCPP_DECLSPEC_EMPTY_BASES
 #  endif
 
 #  if defined(_LIBCPP_ENABLE_CXX17_REMOVED_FEATURES)
 #    define _LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR
 #    define _LIBCPP_ENABLE_CXX17_REMOVED_BINDERS

libcxx/include/__support/win32/limits_msvc_win32.h

-// -*- C++ -*-
-//===-----------------------------------------------------------------------===//
-//
-// 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_WIN32_LIMITS_MSVC_WIN32_H
-#define _LIBCPP_SUPPORT_WIN32_LIMITS_MSVC_WIN32_H
-
-#if !defined(_LIBCPP_MSVCRT)
-#error "This header complements the Microsoft C Runtime library, and should not be included otherwise."
-#endif
-#if defined(__clang__)
-#error "This header should only be included when using Microsoft's C1XX frontend"
-#endif
-
-#include <float.h> // limit constants
-#include <limits.h> // CHAR_BIT
-#include <math.h> // HUGE_VAL
-#include <ymath.h> // internal MSVC header providing the needed functionality
-
-#define __CHAR_BIT__       CHAR_BIT
-
-#define __FLT_MANT_DIG__   FLT_MANT_DIG
-#define __FLT_DIG__        FLT_DIG
-#define __FLT_RADIX__      FLT_RADIX
-#define __FLT_MIN_EXP__    FLT_MIN_EXP
-#define __FLT_MIN_10_EXP__ FLT_MIN_10_EXP
-#define __FLT_MAX_EXP__    FLT_MAX_EXP
-#define __FLT_MAX_10_EXP__ FLT_MAX_10_EXP
-#define __FLT_MIN__        FLT_MIN
-#define __FLT_MAX__        FLT_MAX
-#define __FLT_EPSILON__    FLT_EPSILON
-// predefined by MinGW GCC
-#define __FLT_DENORM_MIN__ 1.40129846432481707092e-45F
-
-#define __DBL_MANT_DIG__   DBL_MANT_DIG
-#define __DBL_DIG__        DBL_DIG
-#define __DBL_RADIX__      DBL_RADIX
-#define __DBL_MIN_EXP__    DBL_MIN_EXP
-#define __DBL_MIN_10_EXP__ DBL_MIN_10_EXP
-#define __DBL_MAX_EXP__    DBL_MAX_EXP
-#define __DBL_MAX_10_EXP__ DBL_MAX_10_EXP
-#define __DBL_MIN__        DBL_MIN
-#define __DBL_MAX__        DBL_MAX
-#define __DBL_EPSILON__    DBL_EPSILON
-// predefined by MinGW GCC
-#define __DBL_DENORM_MIN__ double(4.94065645841246544177e-324L)
-
-#define __LDBL_MANT_DIG__   LDBL_MANT_DIG
-#define __LDBL_DIG__        LDBL_DIG
-#define __LDBL_RADIX__      LDBL_RADIX
-#define __LDBL_MIN_EXP__    LDBL_MIN_EXP
-#define __LDBL_MIN_10_EXP__ LDBL_MIN_10_EXP
-#define __LDBL_MAX_EXP__    LDBL_MAX_EXP
-#define __LDBL_MAX_10_EXP__ LDBL_MAX_10_EXP
-#define __LDBL_MIN__        LDBL_MIN
-#define __LDBL_MAX__        LDBL_MAX
-#define __LDBL_EPSILON__    LDBL_EPSILON
-// predefined by MinGW GCC
-#define __LDBL_DENORM_MIN__ 3.64519953188247460253e-4951L
-
-// __builtin replacements/workarounds
-#define __builtin_huge_vall()    _LInf._Long_double
-#define __builtin_nanl(__dummmy) _LNan._Long_double
-#define __builtin_nansl(__dummy) _LSnan._Long_double
-
-#endif // _LIBCPP_SUPPORT_WIN32_LIMITS_MSVC_WIN32_H

libcxx/include/bit

 #include <__bit/byteswap.h>
 #include <__bits> // __libcpp_clz
 #include <__concepts/arithmetic.h>
 #include <__config>
 #include <limits>
 #include <type_traits>
 #include <version>
 
-#if defined(_LIBCPP_COMPILER_MSVC)
-#  include <intrin.h>
-#endif
-
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD

libcxx/include/charconv

__mul_overflowed(unsigned short __a, _Tp __b, unsigned short& __r)
     return __c > numeric_limits<unsigned short>::max();
 }
 
 template <typename _Tp>
 inline _LIBCPP_HIDE_FROM_ABI bool
 __mul_overflowed(_Tp __a, _Tp __b, _Tp& __r)
 {
     static_assert(is_unsigned<_Tp>::value, "");
-#if !defined(_LIBCPP_COMPILER_MSVC)
     return __builtin_mul_overflow(__a, __b, &__r);
-#else
-    bool __did = __b && (numeric_limits<_Tp>::max() / __b) < __a;
-    __r = __a * __b;
-    return __did;
-#endif
 }
 
 template <typename _Tp, typename _Up>
 inline _LIBCPP_HIDE_FROM_ABI bool
 __mul_overflowed(_Tp __a, _Up __b, _Tp& __r)
 {
     return __mul_overflowed(__a, static_cast<_Tp>(__b), __r);
 }

libcxx/include/limits

 }  // std
 
 */
 
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__config>
 #include <type_traits>
 
-#if defined(_LIBCPP_COMPILER_MSVC)
-#include "__support/win32/limits_msvc_win32.h"
-#endif // _LIBCPP_MSVCRT
-
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 #include <version>
 

libcxx/src/locale.cpp

 const locale::category locale::time;
 const locale::category locale::messages;
 const locale::category locale::all;
 
 class _LIBCPP_HIDDEN locale::__imp
     : public facet
 {
     enum {N = 30};
-#if defined(_LIBCPP_COMPILER_MSVC)
-// FIXME: MSVC doesn't support aligned parameters by value.
-// I can't get the __sso_allocator to work here
-// for MSVC I think for this reason.
-    vector<facet*> facets_;
-#else
     vector<facet*, __sso_allocator<facet*, N> > facets_;
-#endif
     string         name_;
 public:
     explicit __imp(size_t refs = 0);
     explicit __imp(const string& name, size_t refs = 0);
     __imp(const __imp&);
     __imp(const __imp&, const string&, locale::category c);
     __imp(const __imp& other, const __imp& one, locale::category c);
     __imp(const __imp&, facet* f, long id);