Louis Dionne 5d87f60f89 [libc++] Only include_next C library headers when they exist
Some platforms don't provide all C library headers. In practice, libc++
only requires a few C library headers to exist, and only a few functions
on those headers. Missing functions that libc++ doesn't need for its own
implementation are handled properly by the using_if_exists attribute,
however a missing header is currently a hard error when we try to
do #include_next.

This patch should make libc++ more flexible on platforms that do not
provide C headers that libc++ doesn't actually require for its own
implementation. The only downside is that it may move some errors from
the #include_next point to later in the compilation if we actually try
to use something that isn't provided, which could be somewhat confusing.
However, these errors should be caught by folks trying to port libc++
over to a new platform (when running the libc++ test suite), not by end
users.

NOTE: This is a reapplicaton of 226409, which was reverted in 674729813
      because it broke the build. The issue has now been fixed with
      https://reviews.llvm.org/D138062.

Differential Revision: https://reviews.llvm.org/D136683
2022-11-17 10:30:20 -05:00

62 lines
1.2 KiB
C++

// -*- 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_CTYPE_H
#define _LIBCPP_CTYPE_H
/*
ctype.h synopsis
int isalnum(int c);
int isalpha(int c);
int isblank(int c); // C99
int iscntrl(int c);
int isdigit(int c);
int isgraph(int c);
int islower(int c);
int isprint(int c);
int ispunct(int c);
int isspace(int c);
int isupper(int c);
int isxdigit(int c);
int tolower(int c);
int toupper(int c);
*/
#include <__config>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
#if __has_include_next(<ctype.h>)
# include_next <ctype.h>
#endif
#ifdef __cplusplus
#undef isalnum
#undef isalpha
#undef isblank
#undef iscntrl
#undef isdigit
#undef isgraph
#undef islower
#undef isprint
#undef ispunct
#undef isspace
#undef isupper
#undef isxdigit
#undef tolower
#undef toupper
#endif
#endif // _LIBCPP_CTYPE_H