Re: [PULL 04/12] configure: unset harmful environment variables

[Juan Quintela]

Michael Tokarev <mjt@tls.msk.ru> wrote:
> 26.05.2023 19:08, Paolo Bonzini wrote:
> ..
>>   # Unset some variables known to interfere with behavior of common tools,
>> -# just as autoconf does.
>> -CLICOLOR_FORCE= GREP_OPTIONS=
>> -unset CLICOLOR_FORCE GREP_OPTIONS
>> +# just as autoconf does.  Unlike autoconf, we assume that unset exists.
>> +unset CLICOLOR_FORCE GREP_OPTIONS BASH_ENV ENV MAIL MAILPATH CDPATH
>
> Wonder how relevant all this is.
>
> gnu grep (from coreutils) does not document and does not use $GREP_OPTIONS.
>
> While $BASH_ENV is relevant for non-interactive mode (ie, when running as
> a script), but this variable a) is not used when it is invoked as sh (as
> opposed to bash), and b) it is a way to pass actual additional configuration
> to the shell, -- we do not override $PATH, do we? So why we override 
> $BASH_ENV?
> For example, with $BASH_ENV, one can turn on tracing of shell functions, which
> is nearly impossible now when everything is run from within meson.
> Ditto for $ENV.
>
> Others - MAIL and MAILPATH? - those are only relevant for interactive usage,
> and only when mail actually goes to /var/mail/$user (or equivalent), it does
> not matter for scripts at all.
>
> CLICOLOR_FORCE is interesting, and it was there before already.  It looks like
> whomever set that, don't really care about things like ./configure failing due
> to grep et al trying to color-paint its output.  This variable shouldn't be 
> used
> normally, it smells like a single-use thing - eg, to force color when output 
> is
> displayed within less(1), or when grepping output but keeping colors.  If it
> is set in environment before ./configure is run, it's not our fault.
>
> Now we come to CDPATH. But even there, it should not contain something else 
> besides
> "." (current dir) as the first element, it's kinda interesting when CDPATH has
> something else in there.  We've been here for like decades, and this is the
> first time we've hit this.
>
> Do we _really_ need to reset all this? Especially the $ENV and $BASH_ENV 
> thing,
> which are useful..

CDPATH -> It broke my setup, I have had this on my .bashrc since the
90's:

export CDPATH=.:~/work:/scratch/

For the rest, I don't know.  But if autoconf disables them, some weird
system, somewhere in the world makes this fail.

Later, Juan.