On 12 January 2011 01:20, Patrick Horgan wrote:
> On 01/11/2011 02:10 AM, Jonathan Wakely wrote:
>> I wrote this last week, which tames some of the ugliness:
>>
>> #if ((__GNUC__ * 100) + __GNUC_MINOR__)>= 405
>> # define GCC_DIAG_DO_PRAGMA(x) _Pragma (#x)
>> # define GCC_DIAG_PRAGMA(x) GCC_DIAG_DO_PRAGMA(GCC diagnostic x)
>> # if ((__GNUC__ * 100) + __GNUC_MINOR__)>= 406
>> # define GCC_DIAG_OFF(x) GCC_DIAG_PRAGMA(push) \
>> GCC_DIAG_PRAGMA(ignored x)
>> # define GCC_DIAG_ON(x) GCC_DIAG_PRAGMA(pop)
>> # else
>> # define GCC_DIAG_OFF(x) GCC_DIAG_PRAGMA(ignored x)
>> # define GCC_DIAG_ON(x) GCC_DIAG_PRAGMA(warning x)
>> # endif
>> #else
>> # define GCC_DIAG_OFF(x)
>> # define GCC_DIAG_ON(x)
>> #endif
>
> This is great, and supports the use to turn warnings off wonderfully. From
> reading this I assume that 4.5 is the point at which the pragmas were able
> to be put at any scope instead of just file scope. Is this also true for
No, see my follow-up mail.
> #pragma GCC system_header as well, that prior to 4.5 it had to be at file
> scope, but from 4.6 forward it can be at any scope?
As I said in another mail, I'm not sure if the system_header semantics
have changed.
> Also, can I steal, with attribution of course, GCC_DIAG_OFF/ON(x)?
Certainly.
> Also is there an implementation define nesting limit to #pragma GCC
> diagnostic push as there is in the similar microsoft compiler #pragma
> warning push? (Their limit is about 50 I think). That seems like it would
> be plenty, but it's been hit in boost code that was doing tmp.
>
> Also, what if there are too many pops? Is that an error, or ignored?
I don't know, you'll have to try.
> Also did you consider making them so that you could use them like:
>
> GCC_DIAG_OFF(sign-compare)
> if (a< b) {
> GCC_DIAG_ON(sign-compare)
> std::cout<< "a<b\n";
> }
>
>
> just to save the four keystrokes that would be common to all? Something
> like:
>
> #define str(s) #s
> #define joinstr(x,y) str(x ## y)
>
> #if ((__GNUC__ * 100) + __GNUC_MINOR__) >= 405
> # define GCC_DIAG_DO_PRAGMA(x) _Pragma (#x)
> # define GCC_DIAG_PRAGMA(x) GCC_DIAG_DO_PRAGMA(GCC diagnostic x)
> # if ((__GNUC__ * 100) + __GNUC_MINOR__) >= 406
> # define GCC_DIAG_OFF(x) GCC_DIAG_PRAGMA(push) \
> GCC_DIAG_PRAGMA(ignored joinstr(-W,x))
> # define GCC_DIAG_ON(x) GCC_DIAG_PRAGMA(pop)
> # else
> # define GCC_DIAG_OFF(x) GCC_DIAG_PRAGMA(ignored joinstr(-W,x))
> # define GCC_DIAG_ON(x) GCC_DIAG_PRAGMA(warning joinstr(-W,x))
> # endif
> #else
> # define GCC_DIAG_OFF(x)
> # define GCC_DIAG_ON(x)
> #endif
>
> I know it's a little silly, but I get carried away wanting the compiler to
> do stuff for me.
I didn't do that, as my use case is actually much simpler, but it
seems like a nice improvement.
