Re: [configure bus while building] flex beta version 2.5.15

[Bruce Lilly]

Akim Demaille wrote:
> | More configure/autoconf bugs:
> | 
> | 1. configure frequently tests $?, which is usually unnecessary and
> |     always error-prone in a non-interactive shell. 
>
> That's a good one!  Where did you actually find a shell where $?
> cannot be trusted the way Autoconf does?  It's funny that after years
> of use of this feature, nobody would have noticed.
>
>
> |    Additionally, configure should
> | export PS1=""
> |    to ensure that there are no executable commands embedded in the
> |    prompt (which is a source of error when testing $?).
>
> I fail to see the relationship between PS1 and configure, which is a
> noninteractive, non prompt using script.

PS1 might include commands via $(...) or `...`, and in some
versions of some shells that affects $?.  Configure currently
depends on $? *not* being changed by the prompt string,
therefore it must either ensure that the prompt string
contains no executable commands (including within subshells
run from configure), or configure must change to use a
method that is independent of the prompt string content (for
all versions of all shells).  Normally PS1 doesn't include
executable commands, but if $TERM is frequently changed,
something like
PS1='$(tput rev)'"$ "'$(tput sgr0) '
may be useful.  As recently as a couple of months ago, I
encountered a shell where something like that affected $?.