This is the mail archive of the mailing list for the libstdc++ project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Deprecating arithmetic on std::atomic<void*>

On 04/20/2017 11:52 AM, Jonathan Wakely wrote:
On 20/04/17 11:43 +0200, Florian Weimer wrote:
On 04/20/2017 11:25 AM, Jonathan Wakely wrote:

I mean, with -pedantic-errors we already error on void * arighmetics
or function pointer arithmetics.  If std::atomic<void*> would use
the void * arithmetics, it would also reject it. Or does it use integer
arithmetics instead?

No, it does it on void*, but the __atomic built-ins still perform that
arithmetic even with -pedantic-errors.

sizeof is not defined for the relevant types, either, and already triggers a warning by default: warning: invalid application of ‘sizeof’ to a void type [-Wpointer-arith]
  _M_type_size(ptrdiff_t __d) const { return __d * sizeof(_PTp); }

That could be easily avoided if we care about supporting arithmetic on

I think the actual problem here is the suppression of warnings from system headers.

The atomic built-ins still don't warn even with -Wsystem-headers

Sorry, this is what I meant: -pedantic-errors does not catch this case due to the system header warning suppression. Otherwise, with the current std::atomic implementation, -pedantic-errors would already disable the extension on std::atomic alongside with the extension on built-in pointer types, due to the use of sizeof in the definition of _M_type_size.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]