llvm-capstone/libcxx/include/cfloat
Louis Dionne 8cedff10a1 [libc++] Diagnose when header search paths are set up incorrectly
An issue I often see in codebases compiled for unusual platforms is
that header search paths are specified manually and are subtly wrong.
For example, people will manually add `-isystem <some-toolchain>/usr/include`,
which ends up messing up the layering of header search paths required by
libc++ (because the C Standard Library now appears *before* libc++ in
the search paths). Without this patch, this will end up causing
compilation errors that are pretty inscrutable. This patch aims to
improve the user experience by diagnosing this issue explicitly.

In all cases I can think of, I would expect that a compilation error
occur if these header search paths are not layered properly. This
should only provide an explicit diagnostic instead of failing due
to seemingly unrelated compilation errors.

Differential Revision: https://reviews.llvm.org/D131441
2022-08-17 14:05:26 -04:00

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1.9 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_CFLOAT
#define _LIBCPP_CFLOAT
/*
cfloat synopsis
Macros:
FLT_ROUNDS
FLT_EVAL_METHOD // C99
FLT_RADIX
FLT_HAS_SUBNORM // C11
DBL_HAS_SUBNORM // C11
LDBL_HAS_SUBNORM // C11
FLT_MANT_DIG
DBL_MANT_DIG
LDBL_MANT_DIG
DECIMAL_DIG // C99
FLT_DECIMAL_DIG // C11
DBL_DECIMAL_DIG // C11
LDBL_DECIMAL_DIG // C11
FLT_DIG
DBL_DIG
LDBL_DIG
FLT_MIN_EXP
DBL_MIN_EXP
LDBL_MIN_EXP
FLT_MIN_10_EXP
DBL_MIN_10_EXP
LDBL_MIN_10_EXP
FLT_MAX_EXP
DBL_MAX_EXP
LDBL_MAX_EXP
FLT_MAX_10_EXP
DBL_MAX_10_EXP
LDBL_MAX_10_EXP
FLT_MAX
DBL_MAX
LDBL_MAX
FLT_EPSILON
DBL_EPSILON
LDBL_EPSILON
FLT_MIN
DBL_MIN
LDBL_MIN
FLT_TRUE_MIN // C11
DBL_TRUE_MIN // C11
LDBL_TRUE_MIN // C11
*/
#include <__assert> // all public C++ headers provide the assertion handler
#include <__config>
#include <float.h>
#ifndef _LIBCPP_FLOAT_H
# error <cfloat> tried including <float.h> but didn't find libc++'s <float.h> header. \
This usually means that your header search paths are not configured properly. \
The header search paths should contain the C++ Standard Library headers before \
any C Standard Library, and you are probably using compiler flags that make that \
not be the case.
#endif
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
#endif // _LIBCPP_CFLOAT