On 28/07/2023 15:28,  Thierry wrote:
> Yes. But the same engine does things differently between LaTeX
> 2022-11-01 and LaTeX 2023-06-01.
> 
> So could someone give me the diff of the input related things in
> LaTeX between these two versions so that I can have a clue about
> what LaTeX is expecting and what it is eventually calling (because it
> could be calling, low level, the open routine, and there is no
> acrobatics made in the open routine in kerTeX: the handling is made
> before calling the routine; so if LaTeX is calling low level like
> this, the result is not a surprise).

Older LaTeX used \openin + \ifeof to test for file existence; we now use 
\(pdf)filesize, which is expandable and reports "0" for a non-existent 
file. Both methods should find "foo.tex" from "foo" in the same way.

Joseph