[libc-commits] [libc] [libc] Add C23 limits.h header. (PR #78887)

[via libc-commits]

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@@ -0,0 +1,251 @@
+//===-- 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
+
+#if __has_include_next(<limits.h>)
+
+// Suppress `#include_next is a language extension` warnings.
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wgnu-include-next"
+#else // gcc
+#pragma GCC system_header
+#endif // __clang__, __GNUC__
+
+#if defined(__GNUC__) && !defined(__clang__) && !defined(_GCC_LIMITS_H_)
+// The system's limits.h may, in turn, try to #include_next GCC's limits.h when
+// building with GCC.
+// Define the macro _GCC_LIMITS_H_ to stop its chains of #include_next.
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lntue wrote:

Since the current state of those `limits.h` headers is messy, I just remove the `#include_next <limits.h>`, only use compiler supplied macros `__INT_MAX__` and friends, and filling in the rest of C23 `limits.h` macros if missing.

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