Re: snapshot in preparation for m4 1.4.12

[Bruno Haible]

Eric Blake wrote:
> Tom has (graciously) allowed me access to his Irix 5.3 system to attempt
> to address this.

Thanks for debugging this!

> > The test ends up calling sprintf(tmp, "%Ld", -0.0L), but
> 
> excuse the typo; I meant "%Lf", not "%Ld"
> 
> > the system sprintf does not know how to print -0, so the result is
> > 0.000000 and lacks -.  Does it make more sense to adjust the existing
> > gl_PRINTF_INFINITE_LONG_DOUBLE (which also tests for NaN) to add a test
> > for negative zero, or to add a new macro gl_PRINTF_ZERO_LONG_DOUBLE?

Based on this info, I would have recommended to add a separate test to
m4/printf.m4, for clarity; however, in vasnprintf.m4 there are enough
#ifdefs, therefore I would simply have defined NEED_PRINTF_INFINITE_LONG_DOUBLE.

> At any rate, the Irix box also failed the infinite long double test, so it
> already has problem with inf and/or NaN, and the place to add code for
> -0.0 should be relatively easy to locate.

In this situation, m4/printf.m4 needs no changes at all. Find here a
proposed fix:

Bruno


--- lib/vasnprintf.c.orig       2008-09-13 19:02:12.000000000 +0200
+++ lib/vasnprintf.c    2008-09-13 19:01:42.000000000 +0200
@@ -255,11 +255,11 @@
 
 #if NEED_PRINTF_INFINITE_LONG_DOUBLE && !NEED_PRINTF_LONG_DOUBLE && !defined 
IN_LIBINTL
 
-/* Equivalent to !isfinite(x), but does not require libm.  */
+/* Equivalent to !isfinite(x) || x == 0, but does not require libm.  */
 static int
-is_infinitel (long double x)
+is_infinite_or_zerol (long double x)
 {
-  return isnanl (x) || (x + x == x && x != 0.0L);
+  return isnanl (x) || x + x == x;
 }
 
 #endif
@@ -2578,8 +2578,10 @@
 # elif NEED_PRINTF_INFINITE_LONG_DOUBLE
                         || (a.arg[dp->arg_index].type == TYPE_LONGDOUBLE
                             /* Some systems produce wrong output for Inf,
-                               -Inf, and NaN.  */
-                            && is_infinitel 
(a.arg[dp->arg_index].a.a_longdouble))
+                               -Inf, and NaN.  Some systems in this category
+                               (IRIX 5.3) also do so for -0.0.  Therefore we
+                               treat this case here as well.  */
+                            && is_infinite_or_zerol 
(a.arg[dp->arg_index].a.a_longdouble))
 # endif
                        ))
              {