Re: [PATCH] pretty-print: Fix up ptrdiff handling for %tu, %to, %tx

[Jeff Law <jeffreyalaw@gmail.com>]

On 2/13/24 01:21, Jakub Jelinek wrote:
> Hi!
> 
> This is IMHO more of a theoretical case, I believe my current code
> doesn't handle %tu or %to or %tx correctly if ptrdiff_t is not one of
> int, long int or long long int.  For size_t and %zd or %zi I'm
> using va_arg (whatever, ssize_t) and hope that ssize_t is the signed
> type corresponding to size_t which C99 talks about.
> For ptrdiff_t there is no type for unsigned type corresponding to
> ptrdiff_t and I'm not aware of a portable way on the host to get
> such a type (the fmt tests use hacks like
> #define signed /* Type might or might not have explicit 'signed'.  */
> typedef unsigned __PTRDIFF_TYPE__ unsigned_ptrdiff_t;
> #undef signed
> but that only works with compilers which predefine __PTRDIFF_TYPE__),
> std::make_unsigned<ptrdiff_t> I believe only works reliably if
> ptrdiff_t is one of char, signed char, short, int, long or long long,
> but won't work e.g. for __int20__ or whatever other weird ptrdiff_t
> the host might have.
> 
> The following patch assumes host is two's complement (I think we
> rely on it pretty much everywhere anyway) and prints unsigned type
> corresponding to ptrdiff_t as unsigned long long printing of
> ptrdiff_t value masked with 2ULL * PTRDIFF_MAX + 1.  So the only
> actual limitation is that it doesn't support ptrdiff_t wider than
> long long int.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> 2024-02-13  Jakub Jelinek  <jakub@redhat.com>
> 
> 	* pretty-print.cc (PTRDIFF_MAX): Define if not yet defined.
> 	(pp_integer_with_precision): For unsigned ptrdiff_t printing
> 	with u, o or x print ptrdiff_t argument converted to
> 	unsigned long long and masked with 2ULL * PTRDIFF_MAX + 1.
> 
> 	* error.cc (error_print): For u printing of ptrdiff_t,
> 	print ptrdiff_t argument converted to unsigned long long and
> 	masked with 2ULL * PTRDIFF_MAX + 1.
OK
jeff