X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Ftruncf.m4;h=3920fcd469e75e60a6fce7e39ca33540341651f2;hb=39e1adf83f9afbbc1ab9edbd6ca3d509c1f1bec4;hp=ed21f57db5314c473037a8567f2816913f866a45;hpb=3030c5b5e0a5199e16b05927da72c43c42f211c3;p=gnulib.git

diff --git a/m4/truncf.m4 b/m4/truncf.m4
index ed21f57db..3920fcd46 100644
--- a/m4/truncf.m4
+++ b/m4/truncf.m4
@@ -1,11 +1,12 @@
-# truncf.m4 serial 1
-dnl Copyright (C) 2007, 2009 Free Software Foundation, Inc.
+# truncf.m4 serial 5
+dnl Copyright (C) 2007, 2010-2011 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],
 [
+  m4_divert_text([DEFAULTS], [gl_truncf_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   dnl Persuade glibc <math.h> to declare truncf().
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
@@ -14,35 +15,72 @@ AC_DEFUN([gl_FUNC_TRUNCF],
   if test "$ac_cv_have_decl_truncf" = yes; then
     dnl Test whether truncf() can be used without libm.
     TRUNCF_LIBM=?
-    AC_TRY_LINK([
-       #ifndef __NO_MATH_INLINES
-       # define __NO_MATH_INLINES 1 /* for glibc */
-       #endif
-       #include <math.h>
-       float x;],
-      [x = truncf(x);],
+    AC_LINK_IFELSE(
+      [AC_LANG_PROGRAM(
+         [[#ifndef __NO_MATH_INLINES
+           # define __NO_MATH_INLINES 1 /* for glibc */
+           #endif
+           #include <math.h>
+           float x;]],
+         [[x = truncf(x);]])],
       [TRUNCF_LIBM=])
     if test "$TRUNCF_LIBM" = "?"; then
       save_LIBS="$LIBS"
       LIBS="$LIBS -lm"
-      AC_TRY_LINK([
-         #ifndef __NO_MATH_INLINES
-         # define __NO_MATH_INLINES 1 /* for glibc */
-         #endif
-         #include <math.h>
-         float x;],
-        [x = truncf(x);],
+      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
+    m4_ifdef([gl_FUNC_TRUNCF_IEEE], [
+      if test $gl_truncf_required = ieee && test $REPLACE_TRUNCF = 0; then
+        AC_CACHE_CHECK([whether truncf works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_truncf_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $TRUNCF_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_FLOAT_MINUS_ZERO_CODE[
+]gl_FLOAT_SIGNBIT_CODE[
+int main()
+{
+  /* Test whether truncf (-0.0f) is -0.0f.  */
+  if (signbitf (minus_zerof) && !signbitf (truncf (minus_zerof)))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_truncf_ieee=yes],
+              [gl_cv_func_truncf_ieee=no],
+              [gl_cv_func_truncf_ieee="guessing no"])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_truncf_ieee" in
+          *yes) ;;
+          *) REPLACE_TRUNCF=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_DECL_TRUNCF=0
-    AC_LIBOBJ([truncf])
+  fi
+  if test $HAVE_DECL_TRUNCF = 0 || test $REPLACE_TRUNCF = 1; then
+    dnl No libraries are needed to link lib/truncf.c.
     TRUNCF_LIBM=
   fi
-  AC_SUBST([HAVE_DECL_TRUNCF])
   AC_SUBST([TRUNCF_LIBM])
 ])