Am Di., 6. Apr. 2021 um 21:05 Uhr schrieb Paul Eggert <eggert@cs.ucla.edu>:

On 4/5/21 11:48 PM, Marc Nieper-Wißkirchen wrote:
> SIZE_MAX < (uintmax_t) nbytes

Eeuuw! That's a cure worse than the disease. Among other things, there
is no guarantee that PTRDIFF_MAX <= UINTMAX_MAX so in theory the
comparison could go completely awry with a sufficiently-large NBYTES.

I checked the ISO C18 standard before I wrote this. :) In 6.2.5 it says that for every signed type there is an unsigned type of the same width. Given the definitions of INTMAX_MAX and UINTMAX_MAX, I then concluded

PTRDIFF_MAX <= INTMAX_MAX <= UINTMAX_MAX.

Where is the flaw in my reasoning?