Re: indsize: New module

[Paul Eggert]

On 12/3/20 2:02 PM, Bruno Haible wrote:
> For this reason I see the choice of a signed type as an_implementation_  detail.

It's a crucial detail and it belongs in the API. I not not want to waste time 
worrying whether idx_t is signed in any code that uses idx_t, as 
signed-vs-unsigned problems are endemic to C and part of the point of using 
ptrdiff_t is so that I *don't* have to worry about this stuff. For example, if I 
have an int value I and an idx_t value N and I happens to be negative, and I 
don't want to have to worry about the possibility that the expression I < N 
might fail to be true. Expressions like that happen quite a bit in generic code 
and this is a real problem.

If we're going to leave open the possibility that this type might be unsigned, 
I'd rather not use the type in canonicalize.c now. Maybe in a decade or three 
if the C language evolves well in this area, but now's not the time (and I have 
my doubts about whether it'll evolve well).