Re: [PATCH v2 1/1] trace2: NULL is not allowed for va_list

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On 3/19/2019 1:13 PM, tboegi@xxxxxx wrote:
From: Torsten Bögershausen <tboegi@xxxxxx>

Some compilers don't allow NULL to be passed for a va_list,
and e.g. "gcc (Raspbian 6.3.0-18+rpi1+deb9u1) 6.3.0 20170516"
errors out like this:
  trace2/tr2_tgt_event.c:193:18:
    error: invalid operands to binary &&
    (have ‘int’ and ‘va_list {aka __va_list}’)
     if (fmt && *fmt && ap) {
                        ^^
I couldn't find any hints that va_list and pointers can be mixed,
and no hints that they can't either. Morten Welinder comments:

"C99, Section 7.15, simply says that va_list "is an object type suitable for
holding information needed by the macros va_start, va_end, and
va_copy". So clearly not guaranteed to be mixable with pointers...

The portable solution is to use "va_list" everywhere in the callchain.
As a consequence, both trace2_region_enter_fl() and trace2_region_leave_fl()
now take a variable argument list.

Signed-off-by: Torsten Bögershausen <tboegi@xxxxxx>

Looks good.  Thanks for tracking this down.
Jeff


Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>



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