When cross-compiling, I also see this wrong guess:
checking for signbit macro... guessing no
This should fix it. (Most of this patch is merely reindentation.)
2012-05-01 Bruno Haible <br...@clisp.org>
signbit: Avoid "guessing no" when cross-compiling to glibc systems.
* m4/signbit.m4 (gl_SIGNBIT): Require AC_CANONICAL_HOST. When cross-
compiling to a glibc system, set gl_cv_func_signbit to "guessing yes".
--- m4/signbit.m4.orig Wed May 2 00:22:54 2012
+++ m4/signbit.m4 Wed May 2 00:22:51 2012
@@ -1,4 +1,4 @@
-# signbit.m4 serial 11
+# signbit.m4 serial 12
dnl Copyright (C) 2007-2012 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -7,6 +7,7 @@
AC_DEFUN([gl_SIGNBIT],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([for signbit macro], [gl_cv_func_signbit],
[
AC_RUN_IFELSE(
@@ -27,7 +28,13 @@
])],
[gl_cv_func_signbit=yes],
[gl_cv_func_signbit=no],
- [gl_cv_func_signbit="guessing no"])
+ [case "$host_os" in
+ # Guess yes on glibc systems.
+ *-gnu*) gl_cv_func_signbit="guessing yes" ;;
+ # If we don't know, assume the worst.
+ *) gl_cv_func_signbit="guessing no" ;;
+ esac
+ ])
])
dnl GCC 4.0 and newer provides three built-ins for signbit.
dnl They can be used without warnings, also in C++, regardless of <math.h>.
@@ -50,86 +57,91 @@
])],
[gl_cv_func_signbit_gcc=yes],
[gl_cv_func_signbit_gcc=no],
- [gl_cv_func_signbit_gcc="guessing no"])
+ [# If we don't know, assume the worst.
+ gl_cv_func_signbit_gcc="guessing no"
+ ])
])
dnl Use the compiler built-ins whenever possible, because they are more
dnl efficient than the system library functions (if they exist).
if test "$gl_cv_func_signbit_gcc" = yes; then
REPLACE_SIGNBIT_USING_GCC=1
else
- if test "$gl_cv_func_signbit" != yes; then
- dnl REPLACE_SIGNBIT=1 makes sure the signbit[fdl] functions get built.
- REPLACE_SIGNBIT=1
- gl_FLOAT_SIGN_LOCATION
- gl_DOUBLE_SIGN_LOCATION
- gl_LONG_DOUBLE_SIGN_LOCATION
- if test "$gl_cv_cc_float_signbit" = unknown; then
- dnl Test whether copysignf() is declared.
- AC_CHECK_DECLS([copysignf], , , [[#include <math.h>]])
- if test "$ac_cv_have_decl_copysignf" = yes; then
- dnl Test whether copysignf() can be used without libm.
- AC_CACHE_CHECK([whether copysignf can be used without linking with
libm],
- [gl_cv_func_copysignf_no_libm],
- [
- AC_LINK_IFELSE(
- [AC_LANG_PROGRAM(
- [[#include <math.h>
- float x, y;]],
- [[return copysignf (x, y) < 0;]])],
- [gl_cv_func_copysignf_no_libm=yes],
- [gl_cv_func_copysignf_no_libm=no])
- ])
- if test $gl_cv_func_copysignf_no_libm = yes; then
- AC_DEFINE([HAVE_COPYSIGNF_IN_LIBC], [1],
- [Define if the copysignf function is declared in <math.h> and
available in libc.])
+ case "$gl_cv_func_signbit" in
+ *yes) ;;
+ *)
+ dnl REPLACE_SIGNBIT=1 makes sure the signbit[fdl] functions get built.
+ REPLACE_SIGNBIT=1
+ gl_FLOAT_SIGN_LOCATION
+ gl_DOUBLE_SIGN_LOCATION
+ gl_LONG_DOUBLE_SIGN_LOCATION
+ if test "$gl_cv_cc_float_signbit" = unknown; then
+ dnl Test whether copysignf() is declared.
+ AC_CHECK_DECLS([copysignf], , , [[#include <math.h>]])
+ if test "$ac_cv_have_decl_copysignf" = yes; then
+ dnl Test whether copysignf() can be used without libm.
+ AC_CACHE_CHECK([whether copysignf can be used without linking with
libm],
+ [gl_cv_func_copysignf_no_libm],
+ [
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <math.h>
+ float x, y;]],
+ [[return copysignf (x, y) < 0;]])],
+ [gl_cv_func_copysignf_no_libm=yes],
+ [gl_cv_func_copysignf_no_libm=no])
+ ])
+ if test $gl_cv_func_copysignf_no_libm = yes; then
+ AC_DEFINE([HAVE_COPYSIGNF_IN_LIBC], [1],
+ [Define if the copysignf function is declared in <math.h> and
available in libc.])
+ fi
fi
fi
- fi
- if test "$gl_cv_cc_double_signbit" = unknown; then
- dnl Test whether copysign() is declared.
- AC_CHECK_DECLS([copysign], , , [[#include <math.h>]])
- if test "$ac_cv_have_decl_copysign" = yes; then
- dnl Test whether copysign() can be used without libm.
- AC_CACHE_CHECK([whether copysign can be used without linking with
libm],
- [gl_cv_func_copysign_no_libm],
- [
- AC_LINK_IFELSE(
- [AC_LANG_PROGRAM(
- [[#include <math.h>
- double x, y;]],
- [[return copysign (x, y) < 0;]])],
- [gl_cv_func_copysign_no_libm=yes],
- [gl_cv_func_copysign_no_libm=no])
- ])
- if test $gl_cv_func_copysign_no_libm = yes; then
- AC_DEFINE([HAVE_COPYSIGN_IN_LIBC], [1],
- [Define if the copysign function is declared in <math.h> and
available in libc.])
+ if test "$gl_cv_cc_double_signbit" = unknown; then
+ dnl Test whether copysign() is declared.
+ AC_CHECK_DECLS([copysign], , , [[#include <math.h>]])
+ if test "$ac_cv_have_decl_copysign" = yes; then
+ dnl Test whether copysign() can be used without libm.
+ AC_CACHE_CHECK([whether copysign can be used without linking with
libm],
+ [gl_cv_func_copysign_no_libm],
+ [
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <math.h>
+ double x, y;]],
+ [[return copysign (x, y) < 0;]])],
+ [gl_cv_func_copysign_no_libm=yes],
+ [gl_cv_func_copysign_no_libm=no])
+ ])
+ if test $gl_cv_func_copysign_no_libm = yes; then
+ AC_DEFINE([HAVE_COPYSIGN_IN_LIBC], [1],
+ [Define if the copysign function is declared in <math.h> and
available in libc.])
+ fi
fi
fi
- fi
- if test "$gl_cv_cc_long_double_signbit" = unknown; then
- dnl Test whether copysignl() is declared.
- AC_CHECK_DECLS([copysignl], , , [[#include <math.h>]])
- if test "$ac_cv_have_decl_copysignl" = yes; then
- dnl Test whether copysignl() can be used without libm.
- AC_CACHE_CHECK([whether copysignl can be used without linking with
libm],
- [gl_cv_func_copysignl_no_libm],
- [
- AC_LINK_IFELSE(
- [AC_LANG_PROGRAM(
- [[#include <math.h>
- long double x, y;]],
- [[return copysignl (x, y) < 0;]])],
- [gl_cv_func_copysignl_no_libm=yes],
- [gl_cv_func_copysignl_no_libm=no])
- ])
- if test $gl_cv_func_copysignl_no_libm = yes; then
- AC_DEFINE([HAVE_COPYSIGNL_IN_LIBC], [1],
- [Define if the copysignl function is declared in <math.h> and
available in libc.])
+ if test "$gl_cv_cc_long_double_signbit" = unknown; then
+ dnl Test whether copysignl() is declared.
+ AC_CHECK_DECLS([copysignl], , , [[#include <math.h>]])
+ if test "$ac_cv_have_decl_copysignl" = yes; then
+ dnl Test whether copysignl() can be used without libm.
+ AC_CACHE_CHECK([whether copysignl can be used without linking with
libm],
+ [gl_cv_func_copysignl_no_libm],
+ [
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <math.h>
+ long double x, y;]],
+ [[return copysignl (x, y) < 0;]])],
+ [gl_cv_func_copysignl_no_libm=yes],
+ [gl_cv_func_copysignl_no_libm=no])
+ ])
+ if test $gl_cv_func_copysignl_no_libm = yes; then
+ AC_DEFINE([HAVE_COPYSIGNL_IN_LIBC], [1],
+ [Define if the copysignl function is declared in <math.h> and
available in libc.])
+ fi
fi
fi
- fi
- fi
+ ;;
+ esac
fi
])
