zarith and conf-gmp need to be smarter on macos x

[avsm]

gmp.h is in /usr/local/include but there's no pkg-config. So to compile zarith on MacOS X I need to:

LDFLAGS=-L/usr/local/lib CFLAGS=-I/usr/local/include opam install zarith -v

I suspect we need to pkg-config up gmp to make this opam-friendly

[avsm]

and also zmq.h. has something changed on yosemite i wonder...

# 
# /Users/avsm/.opam/4.01.0/bin/ocamlopt.opt unix.cmxa -I /Users/avsm/.opam/4.01.0/lib/ocaml/ocamlbuild /Users/avsm/.opam/4.01.0/lib/ocaml/ocamlbuild/ocamlbuildlib.cmxa myocamlbuild.ml /Users/avsm/.opam/4.01.0/lib/ocaml/ocamlbuild/ocamlbuild.cmx -o myocamlbuild
# /Users/avsm/.opam/4.01.0/bin/ocamlfind ocamlc -ccopt -I -ccopt /Users/avsm/.opam/4.01.0/lib/uint -ccopt -Wall -ccopt -Wextra -ccopt -O2 -c src/caml_zmq_stubs.c
# + /Users/avsm/.opam/4.01.0/bin/ocamlfind ocamlc -ccopt -I -ccopt /Users/avsm/.opam/4.01.0/lib/uint -ccopt -Wall -ccopt -Wextra -ccopt -O2 -c src/caml_zmq_stubs.c
# src/caml_zmq_stubs.c:30:10: fatal error: 'zmq.h' file not found
# #include <zmq.h>
#          ^
# 1 error generated.
# Command exited with code 2.
### stderr ###

[amirmc]

I just hit this issue again on a fresh switch (and came back here for the appropriate incantation). How do we fix this?

[aluuu]

Ran into this issue during following Mirage tutorial screencast.
Defining LDFLAGS and CFLAGS worked for me.

[MagnusS]

It's not possible to override CFLAGS and LDFLAGS on OS X anymore, as they are now set to /usr/local/* in opam. If homebrew/gmp.h is installed in a different location than /usr/local installation fails.

[jbulow]

Macports installs gmp.h in /opt/local/include. Does this mean that opam is broken on OSX and it will not be fixed?

[francesco-zappa-nardelli]

Dear all, I have encountered the same problem of jbulow:

Macports installs gmp.h in /opt/local/include. Does this mean that opam is broken on OSX and it will not be fixed?

This is a showstopper for me. Is there any workaround? (Using brew instead of macport is not something I consider a workaround). Can it / will it be fixed? Thanks.

-francesco

[jbulow]

Still broken in opam2-beta

[psilord]

I have run into the same problem as jbulow as well, any suggestions on a decent workaround to tell opam that /opt/local and /usr/local can both exist at the same time? Thank you!

[dbuenzli]

So basically on macOS by checking two locations it seems that we catch 99% of the install base of gmp.

So in #9728 I simply move to the solution of checking both locations. If I got my shell quoting right I also reinstated the ability @MagnusS mentioned was lost to explicitely specify LDFLAGS and and CFLAGS.

This may not be the best solution but it should work reasonably well for the time being.

The problem should be revisited in opam v2 when packages will be able to set environment variables (and thus extend PKG_CONFIG_PATH) by having simple conf-* packages that create and install .pc file according to where C packages that lack one are discovered.

Using such a custom .pc packages for gmp will allow to use pkg-config in zarith build instructions.

[jberdine]

I just want to note that I ran into a minor issue caused by this fix. As part of debugging some linker trouble, a ld: warning: directory not found for option '-L/opt/local/lib' warning sent me on a bit of a wild goose chase, only to find that it is a spuriously added option by the zarith opam file.

It would be an improvement to add only the directive to the needed path, although I don't know how to reliably achieve that.

[mimoo]

I still get these messages btw