X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Ftrunc.m4;h=079cbcb911f9d76dae78ac3555c830dae115523d;hb=76b501132e66a15451e8d81ced31daf50d2825c3;hp=0654d9cd2140109a55752a204bacc19572dbcd18;hpb=ec062d7a2671739dd977ebde3965fc93f8678a2e;p=gnulib.git

diff --git a/m4/trunc.m4 b/m4/trunc.m4
index 0654d9cd2..079cbcb91 100644
--- a/m4/trunc.m4
+++ b/m4/trunc.m4
@@ -1,16 +1,17 @@
-# trunc.m4 serial 4
-dnl Copyright (C) 2007, 2010 Free Software Foundation, Inc.
+# trunc.m4 serial 9
+dnl Copyright (C) 2007, 2010-2013 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_TRUNC],
 [
+  m4_divert_text([DEFAULTS], [gl_trunc_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   dnl Persuade glibc <math.h> to declare trunc().
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
   dnl Test whether trunc() is declared.
-  AC_CHECK_DECLS([trunc], , , [#include <math.h>])
+  AC_CHECK_DECLS([trunc], , , [[#include <math.h>]])
   if test "$ac_cv_have_decl_trunc" = yes; then
     dnl Test whether trunc() can be used without libm.
     TRUNC_LIBM=?
@@ -40,9 +41,54 @@ AC_DEFUN([gl_FUNC_TRUNC],
     if test "$TRUNC_LIBM" = "?"; then
       TRUNC_LIBM=
     fi
+    m4_ifdef([gl_FUNC_TRUNC_IEEE], [
+      if test $gl_trunc_required = ieee && test $REPLACE_TRUNC = 0; then
+        AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+        AC_CACHE_CHECK([whether trunc works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_trunc_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $TRUNC_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_DOUBLE_MINUS_ZERO_CODE[
+]gl_DOUBLE_SIGNBIT_CODE[
+static double dummy (double f) { return 0; }
+int main (int argc, char *argv[])
+{
+  double (*my_trunc) (double) = argc ? trunc : dummy;
+  /* Test whether trunc (-0.0) is -0.0.  */
+  if (signbitd (minus_zerod) && !signbitd (my_trunc (minus_zerod)))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_trunc_ieee=yes],
+              [gl_cv_func_trunc_ieee=no],
+              [case "$host_os" in
+                         # Guess yes on glibc systems.
+                 *-gnu*) gl_cv_func_trunc_ieee="guessing yes" ;;
+                         # If we don't know, assume the worst.
+                 *)      gl_cv_func_trunc_ieee="guessing no" ;;
+               esac
+              ])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_trunc_ieee" in
+          *yes) ;;
+          *) REPLACE_TRUNC=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_DECL_TRUNC=0
-    AC_LIBOBJ([trunc])
+  fi
+  if test $HAVE_DECL_TRUNC = 0 || test $REPLACE_TRUNC = 1; then
+    dnl No libraries are needed to link lib/trunc.c.
     TRUNC_LIBM=
   fi
   AC_SUBST([TRUNC_LIBM])