On 29/07/2023 06:46, LARONDE Thierry wrote:
> On Fri, Jul 28, 2023 at 08:31:53PM +0100, David Carlisle wrote:
>> On 28/07/2023 19:48, Phelype Oleinik wrote:
>>> because the lookup first checks the name as given
>>
>> actually no.
>>
>> For extensionless files .tex is looked for first  (so readme is not
>> accessible if readme.tex is blocking it)
>>
>>
>> % If this option is set to true, `tex a.b' will look first for a.b.tex
>> % (within each path element), and then for a.b, i.e., we try standard
>> % extensions first.  If this is false, we first look for a.b and then
>> % a.b.tex, i.e., we try the name as-is first.
>> %
>> % Both names are always tried; the difference is the order in which they
>> % are tried.  The setting applies to all searches, not just .tex.
>> %
>> % This setting only affects names being looked up which *already* have
>> % an extension.  A name without an extension (e.g., `tex story') will
>> % always have an extension added first.
>> %
>> % The default is true, because we already avoid adding the standard
>> % extension(s) in the usual cases.  E.g., babel.sty will only look for
>> % babel.sty, not babel.sty.tex, regardless of this setting.
>> try_std_extension_first = t
> 
> I suppose that this behavior is in LaTeX code, not an engine?

That's from texmf.cnf, so affects most engines. (LuaMetaTeX like 
unaffected: I'd have to check.)

Joseph