expm1l lacks precision on musl libc 1.2.2/arm64, musl libc 1.2.2/s390x. Fortunately the configure test meant for Mac OS X and NetBSD already catches it.
2021-01-31 Bruno Haible <br...@clisp.org> expm1l: Document musl libc bug. * doc/posix-functions/expm1l.texi: Document musl libc bug. * m4/expm1l.m4 (gl_FUNC_EXPM1L): Update comment and cross compilation guess. diff --git a/doc/posix-functions/expm1l.texi b/doc/posix-functions/expm1l.texi index 4cd58a8..059d5fc 100644 --- a/doc/posix-functions/expm1l.texi +++ b/doc/posix-functions/expm1l.texi @@ -17,7 +17,7 @@ IRIX 6.5. @item This function produces results which are accurate to only 16 digits on some platforms: -Mac OS X 10.5, NetBSD 8.0. +musl libc 1.2.2/arm64, musl libc 1.2.2/s390x, Mac OS X 10.5, NetBSD 8.0. @end itemize Portability problems not fixed by Gnulib: diff --git a/m4/expm1l.m4 b/m4/expm1l.m4 index 8fe31b5..ec0d907 100644 --- a/m4/expm1l.m4 +++ b/m4/expm1l.m4 @@ -1,4 +1,4 @@ -# expm1l.m4 serial 8 +# expm1l.m4 serial 9 dnl Copyright (C) 2010-2021 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -123,7 +123,8 @@ int main (int argc, char *argv[]) { long double (* volatile my_expm1l) (long double) = argc ? expm1l : dummy; int result = 0; - /* This test fails on Mac OS X 10.5, NetBSD 8.0. */ + /* This test fails on musl 1.2.2/arm64, musl 1.2.2/s390x, Mac OS X 10.5, + NetBSD 8.0. */ { const long double TWO_LDBL_MANT_DIG = /* 2^LDBL_MANT_DIG */ (long double) (1U << ((LDBL_MANT_DIG - 1) / 5)) @@ -147,8 +148,8 @@ int main (int argc, char *argv[]) [case "$host_os" in # Guess yes on glibc systems. *-gnu* | gnu*) gl_cv_func_expm1l_works="guessing yes" ;; - # Guess yes on musl systems. - *-musl*) gl_cv_func_expm1l_works="guessing yes" ;; + # Guess no on musl systems. + *-musl*) gl_cv_func_expm1l_works="guessing no" ;; # Guess yes on native Windows. mingw*) gl_cv_func_expm1l_works="guessing yes" ;; # If we don't know, obey --enable-cross-guesses.