[libc-commits] [libc] [libc] Add limits.h header. (PR #78887)

[via libc-commits]

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@@ -0,0 +1,229 @@
+//===-- Definition of macros from limits.h --------------------------------===//
+//
+// 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 __LLVM_LIBC_MACROS_LIMITS_MACROS_H
+#define __LLVM_LIBC_MACROS_LIMITS_MACROS_H
+
+#ifdef __clang__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wgnu-include-next"
+#endif // __clang__
+
+#include_next <limits.h>
+
+#ifdef __clang__
+#pragma GCC diagnostic pop
+#endif // __clang__
+
+#ifndef CHAR_BIT
+#ifdef __CHAR_BIT__
+#define CHAR_BIT __CHAR_BIT__
+#else
+#define CHAR_BIT 8
+#endif // __CHAR_BIT__
+#endif // CHAR_BIT
+
+// TODO: define MB_LEN_MAX if missing
+//   clang: MB_LEN_MAX = 1 -
+//   https://github.com/llvm/llvm-project/blob/main/clang/lib/Headers/limits.h#L64
+//   glibc: MB_LEN_MAX = 16 -
+//   https://github.com/lattera/glibc/blob/master/include/limits.h#L32
+
+// *_WIDTH macros
+
+#ifndef CHAR_WIDTH
+#define CHAR_WIDTH CHAR_BIT
+#endif // CHAR_WIDTH
+
+#ifndef SCHAR_WIDTH
+#define SCHAR_WIDTH CHAR_BIT
+#endif // SCHAR_WIDTH
+
+#ifndef UCHAR_WIDTH
+#define UCHAR_WIDTH CHAR_BIT
+#endif // UCHAR_WIDTH
+
+#ifndef SHRT_WIDTH
+#ifdef __SHRT_WIDTH__
+#define SHRT_WIDTH __SHRT_WIDTH__
+#else
+#define SHRT_WIDTH 16
+#endif // __SHRT_WIDTH__
+#endif // SHRT_WIDTH
+
+#ifndef USHRT_WIDTH
+#define USHRT_WIDTH SHRT_WIDTH
+#endif // USHRT_WIDTH
+
+#ifndef INT_WIDTH
+#ifdef __INT_WIDTH__
+#define INT_WIDTH __INT_WIDTH__
+#else
+#define INT_WIDTH 32
+#endif // __INT_WIDTH__
+#endif // INT_WIDTH
+
+#ifndef UINT_WIDTH
+#define UINT_WIDTH INT_WIDTH
+#endif // UINT_WIDTH
+
+#ifndef LONG_WIDTH
+#ifdef __LONG_WIDTH__
+#define LONG_WIDTH __LONG_WIDTH__
+#elif defined(__WORDSIZE)
+#define LONG_WIDTH __WORDSIZE
+#else
+#error "Unknown WORDSIZE to define LONG_WIDTH."
+#endif // __LONG_WIDTH__
+#endif // LONG_WIDTH
+
+#ifndef ULONG_WIDTH
+#define ULONG_WIDTH LONG_WIDTH
+#endif // ULONG_WIDTH
+
+#ifndef LLONG_WIDTH
+#ifdef __LLONG_WIDTH__
+#define LLONG_WIDTH __LLONG_WIDTH__
+#else
+#define LLONG_WIDTH 64
+#endif // __LLONG_WIDTH__
+#endif // LLONG_WIDTH
+
+#ifndef ULLONG_WIDTH
+#define ULLONG_WIDTH LLONG_WIDTH
+#endif // ULLONG_WIDTH
+
+#ifndef BOOL_WIDTH
+#ifdef __BOOL_WIDTH__
+#define BOOL_WIDTH __BOOL_WIDTH__
+#else
+#define BOOL_WIDTH 1
+#endif // __BOOL_WIDTH__
+#endif // BOOL_WIDTH
+
+// *_MAX macros
+
+#ifndef SCHAR_MAX
+#ifdef __SCHAR_MAX__
+#define SCHAR_MAX __SCHAR_MAX__
+#else
+#define SCHAR_MAX 0x7f
+#endif // __SCHAR_MAX__
+#endif // SCHAR_MAX
+
+#ifndef UCHAR_MAX
+#define UCHAR_MAX (SCHAR_MAX * 2 + 1)
+#endif // UCHAR_MAX
+
+#ifndef CHAR_MAX
+#ifdef __CHAR_UNSIGNED__
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lntue wrote:

Do you know any compiler failed to define `__CHAR_UNSIGNED__` on such platforms?  I would assume gcc and clang are correct with this flag.

https://github.com/llvm/llvm-project/pull/78887