Re: misleading output from AC_PROG_AWK

[Ralf Wildenhues]

Hi Eric,

* Eric Blake wrote on Fri, Jun 20, 2008 at 02:08:46PM CEST:
> According to Ralf Wildenhues on 6/19/2008 11:42 AM:
>> | checking for gawk... (user-provided) awk
>>
>> One drawback is that this may be wrong, too, for example when AWK
>> is passed from one configure script to the next (maybe "(set in $AWK)"
>> instead?).
>
> Now that seems like a relatively simple idea.  So the possible output  
> cases would be:
>
> user did nothing, and awk is the final program found after a full search:
> | checking for gawk... awk
>
> user did nothing, and the cache was used:
> | checking for gawk... (cached) awk
>
> user supplied AWK:
> | checking for gawk... (set in $AWK) awk
>
> Here's where to stick a one-liner patch that would do this (although I  
> haven't tested it, so it may need some quoting adjustments, and certainly 
> needs a testsuite addition); does this approach sound good enough to  
> pursue further?

Well, it needed a backslash before the first $.  Let's look at a first
practice test:

$ ../autoconf/configure -C M4=/usr/bin/m4 EMACS=emacs \
        EXPR=/usr/bin/expr PERL=/usr/bin/perl
| configure: creating cache config.cache
[...]
| checking for expr... /usr/bin/expr
| checking for GNU M4 that supports accurate traces... /usr/bin/m4
| checking how m4 supports trace files... --debugfile
| checking for perl... /usr/bin/perl
| checking for emacs... (set in $TEST_EMACS) emacs
| checking whether emacs is sufficiently recent... yes
| checking for emacs... (set in $EMACS) emacs
[...]

Hmm.  M4, EXPR, and PERL are not designated at all, and mention of
TEST_EMACS is confusing at best.  As much as I liked the initial idea,
the result of this isn't too good yet.  With improved output, the user
will come to expect consistency in the improvement as well; and that
both requires more work in Autoconf, as well as work on the part of the
configure.ac author as well.

I haven't yet thought through whether this is fixable nicely or not.

Cheers, and thanks for your valuable input,
Ralf