Re: AC_REQUIRE problems

[Dan Manthey]

On Wed, 16 Feb 2005, Stepan Kasal wrote:

> An idea:
> I don't believe it's worth the work to have configure to run the individual
> tests in parallel.  If someone is able to invent a way to get several
> independent results from one run of compiler/preprocessor, that would
> help substantially.  (Even if the trick works for certain compilers only,
> it would be worth it to put the two alternative methods to the generated
> `configure'.)
>

        Well, trivially, it's possible to run an arbitrary number of tests
together and see if _none_ of them fail: `cc foo.c bar.c'  and then only
run them separately if there is a failure.  it might also be possible with
some known compilers (e.g. gcc) to grep the error output for file names.
i.e., early on try `cc -c okay1.c okay2.c' to see if you can compile multiple
files, then try `cc -c okay.c bad.c' and grep for the names `okay' and
`bad' to see if you can check where the error is.  Even if you can't
figure out which file has an error, it could speed up the common case of
no errors.

        This would of course significantly complicate the use of tests,
because we'd have to find a way to accumulate several tests and then use
their results piecewise.  Again, this is further complicated by
only-sometimes-run tests.  It's possible that that could be solved by a
consistant use of A[CS]_IF instead of plain sh if.

        By the way, would it be possible to _detect_ (though surely not
solve) several of the conditional macro problems by having m4 macros `if'
and `fi' and having them expand to some record keeping and the strings
`if' and `fi'?  (I realize that there are viscious complications with C
`if'.)

-Dan