Re: [PATCH] Generic mechanism to detect shell features

[Paolo Bonzini]

Eric, thanks for the thorough review; however the $SHELL problem is serious in 
that
you cannot afford running the tests from within the current shell because of 
syntax
errors.  Maybe eval can help?  You need to make the parent shell parse the shell
functions test without possibly failing.

So my review which would simplify the code makes it incorrect.  Sorry, I must 
have
missed the discussion about $SHELL.

> Problem 3: Inconsistency.  The code sets CONFIG_SHELL to SHELL if SHELL
> passes _both_ required and suggested feature tests; yet it sets CONFIG_SHELL
> to one of the other shells (sh, sh5, ksh, zsh, bash) if it passes only the
> required feature test.  Why the inconsistency?  Why are the requirements
> placed upon SHELL more strict than the requirements for the other shells?

Because if $SHELL was the current shell, this algorithm and the reordering the 
shells
adds an implicit "suggested" feature, i.e. that the shell be ksh, zsh or bash.

> Problem 7: I have not yet tracked down the exact cause of this problem, but
> in the generated configure script, wherever _AS_DETECT_SUGGESTED_FEATURES()
> has been invoked, the _AS_LINENO_WORKS test is emitted twice.  For instance,
> in the generated configure script, I see this:

The problem is that _AS_LINENO_PREPARE is called when outputting config.status 
as
well.

Paolo