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# truncf.m4 serial 3
dnl Copyright (C) 2007, 2010 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_TRUNCF],
[
  AC_REQUIRE([gl_MATH_H_DEFAULTS])
  dnl Persuade glibc <math.h> to declare truncf().
  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
  dnl Test whether truncf() is declared.
  AC_CHECK_DECLS([truncf], , , [#include <math.h>])
  if test "$ac_cv_have_decl_truncf" = yes; then
    dnl Test whether truncf() can be used without libm.
    TRUNCF_LIBM=?
    AC_LINK_IFELSE(
      [AC_LANG_PROGRAM(
         [[#ifndef __NO_MATH_INLINES
           # define __NO_MATH_INLINES 1 /* for glibc */
           #endif
           #include <math.h>
           float x;]],
         [[x = truncf(x);]])],
      [TRUNCF_LIBM=])
    if test "$TRUNCF_LIBM" = "?"; then
      save_LIBS="$LIBS"
      LIBS="$LIBS -lm"
      AC_LINK_IFELSE(
        [AC_LANG_PROGRAM(
           [[#ifndef __NO_MATH_INLINES
             # define __NO_MATH_INLINES 1 /* for glibc */
             #endif
             #include <math.h>
             float x;]],
           [[x = truncf(x);]])],
        [TRUNCF_LIBM="-lm"])
      LIBS="$save_LIBS"
    fi
    if test "$TRUNCF_LIBM" = "?"; then
      TRUNCF_LIBM=
    fi
  else
    HAVE_DECL_TRUNCF=0
    AC_LIBOBJ([truncf])
    TRUNCF_LIBM=
  fi
  AC_SUBST([TRUNCF_LIBM])
])