Hi Eugene, On Wed, Dec 17, 2025 at 03:42:28PM +0100, Eugene Syromyatnikov wrote: > On Wed, Dec 17, 2025 at 2:51 PM Alejandro Colomar <[email protected]> wrote: > > > > +Otherwise, > > +the behavior was undefined. > > I think this statement is incorrect, or at least misleading, because > the current reading (that includes DR460) of ISO 9899:2011 explicitly
Does DR460 retroactively fix C11, or is it incorporated as part of C17? Can you please provide any links to the sources? > states that the function must fail when the condition is not satisfied > (and that is what OpenBSD has implemented), and that also makes any > permissive specification non-conforming wrt C11 as it is now. What do you mean by "permissive specification"? I didn't understand this sentence well. > But that > is also true that C11 _used to_ specify a failure to conform to this > onerous restriction as UB, which rendered the programs malformed, but, > on the other hand, kept libcs that implemented it permissively > standard-conformant. > > I understand that I am unnecessarily conscientious here, Please, be very picky. That'll result in a better manual page. :) > but I think > it is important to articulate what the standard both says and used to > say, as it is the reference point for the language implementations, To some degree, I agree. Except that the standard isn't that important where it differs from reality. > the totality of which an application developer can neither observe nor > inspect, and relying on a couple of anecdotes in terms of > implementations may lead to issues down the road. I guess the outcome > of my rants is "don't use aligned_alloc and C11 together", or > something along those lines. > > > +.IP \[bu] > > +If > > +.I alignment > > +was not a power of two, > > +the behavior was undefined. > > I can't find a version of the standard that mentions the power-of-two > restriction, it pertains only posix_memalign. Oops, you're right; this should be "if the alignment was an unsupported value". Have a lovely day! Alex -- <https://www.alejandro-colomar.es>
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