Re: FREAD_READS_DIRECTORIES test fails for the wrong reasons

[Jeff King <peff@peff.net>]

On Fri, Apr 06, 2018 at 02:06:50PM -0400, Jonathan Primrose wrote:

> A while ago, the configure test for FREAD_READS_DIRECTORIES was changed
> to (attempt to) check for a NULL result from fopen. Unfortunately, the
> test will always fail - because it won't compile. The code snippet in
> configure.ac translates to:
> 
> return f);
> 
> Either there's an extra ) or a missing (. A cast to int wouldn't hurt
> either.

Oops. This is due to my 3adf9fdecf (configure.ac: loosen
FREAD_READS_DIRECTORIES test program, 2017-06-14).

Neither I nor the original tester noticed, because we're on Linux, which
needs that set.

> I'd supply a patch to fix this, but I'm not sure what the results of
> suddenly fixing the test would be. It seems to work well on my
> machine, but I don't stress git much here, and it's just one machine.

I think it should be fixed (and agreed on the "int" thing; the return
value should be "f != NULL" or similar).

I don't know autoconf very well, but is there a way to invoke it that
will let us know if a test-program fails to compile at all? Obviously
for probing the system compler/includes, "does not compile" is an
expected possible outcome. But for tests like this it's really a
tristate: yes, no, or something went horribly wrong.

-Peff