errno-h: document Haiku errors can’t be -1
[gnulib.git] / lib / isnanl-nolibm.h
blob0fb679ecf6508775fc56dd3557da4ce5141c7786
1 /* Test for NaN that does not need libm.
2 Copyright (C) 2007-2025 Free Software Foundation, Inc.
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
9 This file is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17 /* This file uses HAVE_ISNANL_IN_LIBC. */
18 #if !_GL_CONFIG_H_INCLUDED
19 #error "Please include config.h first."
20 #endif
22 #if HAVE_ISNANL_IN_LIBC
23 /* Get declaration of isnan macro or (older) isnanl function. */
24 # include <math.h>
25 # if (__GNUC__ >= 4) || (__clang_major__ >= 4)
26 /* GCC >= 4.0 and clang provide a type-generic built-in for isnan.
27 GCC >= 4.0 also provides __builtin_isnanl, but clang doesn't. */
28 # undef isnanl
29 # define isnanl(x) __builtin_isnan ((long double)(x))
30 # elif defined isnan
31 # undef isnanl
32 # define isnanl(x) isnan ((long double)(x))
33 # endif
34 #else
35 /* Test whether X is a NaN. */
36 # undef isnanl
37 # define isnanl rpl_isnanl
38 extern
39 # ifdef __cplusplus
40 "C"
41 # endif
42 int isnanl (long double x);
43 #endif
45 /* Tell <math.h> that our isnanl does not need libm. */
46 #define HAVE_ISNANL_NOLIBM 1