Re: flex 2.5.31 filter.c bug and patch

[John]

> On some systems filter.c fails to compile because stdin and stdout are
> never guaranteed to be lvalues (see ANSI C), but filter.c expects them
> them to be lvalues:
...
> *** filter.c.orig       Tue Mar 25 11:39:08 2003
> --- filter.c    Wed Apr 16 15:45:00 2003
> ***************
> *** 158,166 ****
>                         int     r;
>
>                         /* setup streams again */
> !                       if ((stdin = fdopen (0, "r")) == NULL)
>                                 flexfatal (_("fdopen(0) failed"));
> !                       if ((stdout = fdopen (1, "w")) == NULL)
>                                 flexfatal (_("fdopen(1) failed"));
>
>                         if ((r = chain->filter_func (chain)) == -1)
> --- 158,166 ----
>                         int     r;
>
>                         /* setup streams again */
> !                       if (fdopen (0, "r") == NULL)
>                                 flexfatal (_("fdopen(0) failed"));
> !                       if (fdopen (1, "w") == NULL)
>                                 flexfatal (_("fdopen(1) failed"));
>
>                         if ((r = chain->filter_func (chain)) == -1)


Thanks. We are aware of this problem. Linux allows stdin and stdout to
be lvalues, but the rest of the world, including ANSI, does not
guarantee it. The above patch won't work, by the way, because stdin
and stdout are not always connected to file descriptors 0 and 1,
respectively. -John