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I'm porting a legacy application from HP-UX to Linux. The va_start macro
takes one argument under HP-UX, but takes two under Linux:

va_start under HP-UX takes only one var:

hp:/home/fred> grep va_start
/ndata1/scratch/gcc-3.2/binutils/include/mpw/>
#define va_start(list) list = (char *) &va_alist


va_start under linux takes two:

linux:/home/fred> grep -i va_start
/usr/lib/gcc/i386-redhat-linux/4.1.1/include/stdarg.h
#define va_start(v,l) __builtin_va_start(v,l)


The errors I'm seeing are listed below. What would be the best way to
handle the discrepancy in va_start between the two systems?


>make
lprintf.c: In function 'lprintf':
lprintf.c:73: error: expected declaration specifiers before 'va_dcl'
lprintf.c:89:13: error: macro "va_start" requires 2 arguments, but only
1 given
lprintf.c:145: error: expected '=', ',', ';', 'asm' or '__attribute__'
before 'va_dcl'
lprintf.c:161:13: error: macro "va_start" requires 2 arguments, but only
1 given
lprintf.c:218: error: expected '=', ',', ';', 'asm' or '__attribute__'
before 'va_dcl'
lprintf.c:234:13: error: macro "va_start" requires 2 arguments, but only
1 given
lprintf.c:284: error: expected '{' at end of input
make[1]: *** [lprintf.o] Error 1
make: *** [upper] Error 2

James Egan said:

> I'm porting a legacy application from HP-UX to Linux. The va_start macro
> takes one argument under HP-UX, but takes two under Linux:

In standard C, va_start takes two arguments, the first being the name of
the object with type 'va_list', and the second being the name of the
last-named parameter in the function parameter list.

One possibility is to invoke your HP-UX compiler in conforming mode (in
which case it must accept the two arguments, because otherwise it doesn't
conform). If that won't wash for you, you could try conditional
compilation, I guess.

<snip>

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

On Mar 24, 8:24*pm, James Egan <jegan...@comcast.net> wrote:
> I'm porting a legacy application from HP-UX to Linux. *The va_start macro
> takes one argument under HP-UX, but takes two under Linux:
>
> va_start under HP-UX takes only one var:
>
> hp:/home/fred> grep va_start
> /ndata1/scratch/gcc-3.2/binutils/include/mpw/>
> #define va_start(list) list = (char *) &va_alist
>
> va_start under linux takes two:
>
> linux:/home/fred> grep -i va_start
> /usr/lib/gcc/i386-redhat-linux/4.1.1/include/stdarg.h
> #define va_start(v,l) * __builtin_va_start(v,l)
>
> The errors I'm seeing are listed below. *What would be the best way to
> handle the discrepancy in va_start between the two systems?
>
> >make
>
> lprintf.c: In function 'lprintf':
> lprintf.c:73: error: expected declaration specifiers before 'va_dcl'
> lprintf.c:89:13: error: macro "va_start" requires 2 arguments, but only
> 1 given
> lprintf.c:145: error: expected '=', ',', ';', 'asm' or '__attribute__'
> before 'va_dcl'
> lprintf.c:161:13: error: macro "va_start" requires 2 arguments, but only
> 1 given
> lprintf.c:218: error: expected '=', ',', ';', 'asm' or '__attribute__'
> before 'va_dcl'
> lprintf.c:234:13: error: macro "va_start" requires 2 arguments, but only
> 1 given
> lprintf.c:284: error: expected '{' at end of input
> make[1]: *** [lprintf.o] Error 1
> make: *** [upper] Error 2

To see an example of how to portably write a varadic function (for
instance to print stuff to a log file) see the C-FAQ starting at
section 15.4 and running over the next few items.

James Egan <> writes:
> I'm porting a legacy application from HP-UX to Linux. The va_start macro
> takes one argument under HP-UX, but takes two under Linux:
>
> va_start under HP-UX takes only one var:
>
> hp:/home/fred> grep va_start
> /ndata1/scratch/gcc-3.2/binutils/include/mpw/>
> #define va_start(list) list = (char *) &va_alist
>
>
> va_start under linux takes two:
>
> linux:/home/fred> grep -i va_start
> /usr/lib/gcc/i386-redhat-linux/4.1.1/include/stdarg.h
> #define va_start(v,l) __builtin_va_start(v,l)
[snip]

The old pre-standard <varargs.h> interface defines a va_start macro
that takes one argument ("man varargs" on your HP-UX system for
details).

The <stdarg.h> interface was introduced in the 1989 ANSI C standard,
if not earlier. In that interface, va_start is a macro that takes
two arguments.

The <varargs.h> interface is still supported on some systems to
support legacy programs, but <stdarg.h> is the right interface to use.

If at all possible, I suggest modifying the application so it uses
<stdarg.h>, which I'm 99.9% sure you'll find is supported on HP-UX.

If that's not practical, you *might* be able to find an implementation
of the old <varargs.h> for Linux, probably one built on top of
<stdarg.h>. If that's what you need, a Linux newsgroup would be more
likely to help you find it.

--
Keith Thompson (The_Other_Keith) <kst->
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"