-----Original Message-----
From: Ángel González
Sent: Monday, January 28, 2013 2:17 AM
To: sisyphus1@xxxxxxxxxxxxxxx
Cc: gcc-help@xxxxxxxxxxx
Subject: Re: null argument where non-null required (argument 2)
On 27/01/13 04:01, sisyphus1@xxxxxxxxxxxxxxx wrote:
For anyone interested (and in case it might be of relevance), using
-Wall, I get the warning when I do:
if(strcmp("Math::BigInt", HvNAME(SvSTASH(SvRV(x))))) { .... }
yet, if I break that into 2 lines:
const char * h = HvNAME(SvSTASH(SvRV(x)));
if(strcmp("Math::BigInt", h)) { .... }
no such warning is emitted.
What's the expansion of HvNAME(SvSTASH(SvRV(x))); ? Is it possible that
it expands to a conditional which in one of the branches returns null?
(although never taken in this specific instance)
I would think that is so. (I haven't actually waded through the plethora of
macros, but I would be very surprised if that's not the case.)
In many instances it *does* return null.
Would that be all that's needed to trigger the warning ?
If so, what are my options regarding silencing the warning ?
There's no such warning if I do:
/* x is an int arg passed to the sub - could be any value */
const char *h = x == 0 ? NULL : "Math::BigInt";
if(strcmp("Math::BigInt", h)) { .... }
And there's not even a warning if I do:
const char *h = NULL;
if(strcmp("Math::BigInt", h)) { .... }
Thanks for the reply, Ángel.
Cheers,
Rob
