m4/isinf.m4

   1 # isinf.m4 serial 4
   2 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
   3 dnl This file is free software; the Free Software Foundation
   4 dnl gives unlimited permission to copy and/or distribute it,
   5 dnl with or without modifications, as long as this notice is preserved.
   6
   7 AC_DEFUN([gl_ISINF],
   8 [
   9   AC_REQUIRE([gl_MATH_H_DEFAULTS])
  10   dnl Persuade glibc <math.h> to declare isinf.
  11   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
  12   AC_CHECK_DECLS([isinf], , , [#include <math.h>])
  13   if test "$ac_cv_have_decl_isinf" = yes; then
  14     gl_CHECK_MATH_LIB([ISINF_LIBM], [x = isinf (x);])
  15     if test "$ISINF_LIBM" != missing; then
  16       dnl Test whether isinf() on 'long double' works.
  17       gl_ISINFL_WORKS
  18       case "$gl_cv_func_isinfl_works" in
  19         *yes) ;;
  20         *)    ISINF_LIBM=missing;;
  21       esac
  22     fi
  23   fi
  24   if test "$ac_cv_have_decl_isinf" != yes ||
  25      test "$ISINF_LIBM" = missing; then
  26     REPLACE_ISINF=1
  27     dnl No libraries are needed to link lib/isinf.c.
  28     ISINF_LIBM=
  29   fi
  30   AC_SUBST([ISINF_LIBM])
  31 ])
  32
  33 dnl Test whether isinf() correctly returns false for LDBL_MAX.
  34 AC_DEFUN([gl_ISINFL_WORKS],
  35 [
  36   AC_REQUIRE([AC_PROG_CC])
  37   AC_REQUIRE([gl_BIGENDIAN])
  38   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  39   AC_CACHE_CHECK([whether isinf(long double) works], [gl_cv_func_isinfl_works],
  40     [
  41       AC_RUN_IFELSE([AC_LANG_PROGRAM([[#include <float.h>
  42                                        #include <math.h>]],
  43                                      [[return !!isinf(LDBL_MAX);]])],
  44                     [gl_cv_func_isinfl_works=yes],
  45                     [gl_cv_func_isinfl_works=no],
  46                     [gl_cv_func_isinfl_works="guessing no"])
  47     ])
  48 ])