No, you're right -- It is pkg-config. I guess my mind was automatically
rejecting kebab case after looking at so much C code. Anyway, whoever
maintains the libffi package for Arch is a butt for not just throwing a
link to ffi.h into /usr/include/ like a sane person.

A couple things in your patch needed to be changed to get the new test to
work properly on my system.
First, I had to alter the conftest for libffi. On my system, the return
result of a true boolean is 1 (which is EXIT_FAILURE in GNU libc) so I
altered it to use the POSIX success/failure macros defined in stdlib.h.
EXTRA_CFLAFGS also needed to be changed to EXTRA_FLAGS and I removed the
'set -x' error trace line. With these changes, the configure script finds
my libffi and everything passes during 'make tests'.

I'm including my patch as an attachment because I had a little trouble
getting the one you sent me to work properly after copying and pasting.
Thanks for addressing my issue so quickly! I'm looking forward to playing
what looks like an amazing pair of languages.

On Tue, Jul 4, 2017 at 7:04 PM, Kaz Kylheku <kaz@kylheku.com> wrote:

> [This is a fwd; the original reply went to the mailing list but bounced
> when trying to reach you.]
>
> [I set Reply-To: which I normally wouldn't do.]
>
> Hi Joe,
>
> Thanks for the report.
>
> I will fix the double definition of ffi_sint.  I regularly build TXR as
> C++, but I didn't test the combination "g++ and libffi missing"!
>
> The configure script currently doesn't test for anything other than
> whether -lffi is needed for linking; the test program is hard coded to #include
> <ffi.h>. That's the include syntax used in all the libffi documentation,
> so I didn't bother detecting the location.
>
> TXR hasn't used anything so far that would require a big hammer like
> pkg-config. (Is it really called pkg_config on Arch, by the way?)
>
> In the future, hopefully, we can avoid bogging down TXR with dependencies
> by using this nice FFI I developed.
>
> I will change the test so it tries things exactly as it does now, and then
> falls back on pkg-config if those approaches fail to compile and link the
> test program.
>
> Cheers ...
>
> On 04.07.2017 14:37, Joe Eib wrote:
>
> After receiving the following error during 'make_tests'
>
> ...
>  TXR tests/017/glob-carray.tl-> tst/tests/017/glob-carray.out
> ./txr: unhandled exception of type error:
> ./txr: ffi-type-compile: unrecognized type specifier: closure
> ./txr: during evaluation at tests/017/glob-carray.tl:30 of form [mapcar
> ffi-type-compile
>                                                                   '(str
> int closure
>
> (ptr-out glob-t))]
> make: *** [Makefile:356: tst/tests/017/glob-carray.out] Error 1
>
> After a little digging I noticed that your configure script fails to
> detect my libffi because Arch Linux installs libffi.h in a nonstandard
> location. I don't know exactly what you're testing for there on line 2845
> of configure but why not just use 'pkg_config --exists libffi' or the
> PKG_CHECK_EXISTS macro and then get the compiler and linker flags directly
> from pkg_config?
>
> Also, when I was trying to find the source of the issue, I compiled txr
> with g++ just for the hell of it and discovered that ffi_type_sint is
> declared twice on lines 141 and 144 which throws an error in g++.
>
>
>
>