On Thu, 11 Aug 2005, Norman Gray wrote:

>> 2. I'm playing with a g95 and I'm getting trouble with the autoconf tests.
>> Specifically:
>>
>> eg in astrom:
>>
>> configure:4187: WARNING: Use AC_PROG_FC with AC_PROG_FPP, instead of
>> AC_PROG_F77
>
> This is the result of a `if test "X$F77" != X; then' test, and so would be
> triggered if there is a $F77 defined in the environment. No, it's not a very
> sensible test....

Okay. I set both $FC and $F77 (both to the same value). I'll stop doing
that. I note that 'g95' is not in the known list of compilers (gfortran
is). This is silly given that g95 works and gfortran doesn't.

>
> If you want to override a non-f77 compiler, you should define FC=xxx in a
> ./configure argument.
>

That's what I did. Just did both though.

Unsetting $F77 does indeed remove that warning (although the warning could
be a bit more specific!)

> This might be harder. I have a note from Toby which suggests that there's a
> larger mess here:

All I want is $FCFLAGS to be included in the preprocessor tests :-(

> What this means is that (a) I'll have to mail Toby to try to get him to
> commit his recent changes onto the dev-nxg-20040116-add-fpp-support branch,
> and to brace himself for some arguments when we do put the patches in (he's
> already anticipated that this will have to be a two-man job on the list), and
> (b) you/we might as well hack away at the fortran.m4 that's on the HEAD,
> because it's probably doomed.

Wibble. I had a look at fortran.m4 and I couldn't even work out how the
tests were created. It seemed to just set a variable and that was it.

> So, without having a completely convincing story of what's going on, I
> suspect that the problem you describe is falling foul of this somewhere. At
> least, it might be worth replacing $FFLAGS with $FCFLAGS each time
> ac_fpp_{compile,link} is set, making sure that FCFLAGS is set to the 64-bit
> options you need, and seeing what happens. If that works on the HEAD, then
> you or I could make the same fix on the dev branch, albeit with the
> expectation that it'll be stomped on by a more substantial/robust rewrite at
> some point in the near future.

If I set $FFLAGS things don't get any further so I don't think that's the
fix.

> How does that sound?
>

More complicated than expected? I've attached the config.log for astrom
for clarity. It's funny how it gives up on g95-64 and then tries to
fallback to g77 -E in conjunction with g95 and then forgets the $FCFLAGS.

Note that the test for "preprocessable Fortran" passes (because it uses
$FCFLAGS) but the next test 'checking for fixed form Fortran preprocessor
features' fails because no $FFLAGS.

So the tests are fundamentally half-baked and inconsistent rather than
being completely wrong.

--
Tim Jenness
JAC software
http://www.jach.hawaii.edu/~timj