Re: [Caml-list] Problem with: opam install conf-openblas (openSUSE 13.2, OCaml 4.06.1, opam 1.2.2)

[Gabriel Scherer <gabriel.scherer@gmail.com>]

Dear Nicolas,

Your question is a bit specialized, and I think it would be a better
fit as an opam-repository issue

  https://github.com/ocaml/opam-repository/issues

or an email to the maintainer of the conf-openblas package (let me cc:
the maintainer, Liang Wang, here)

  https://opam.ocaml.org/packages/conf-openblas/

That said, here would be an approach to answer it: you can find in the
source of the conf-openblas "opam" file (available from the link
above)

  https://github.com/ocaml/opam-repository/blob/master/packages/conf-openblas/conf-openblas.0.2.0/opam

the list of tests that are done on the user's machine to test whether
openblas is accessible. Currently the tests are as follows:

build: [
["sh" "-exc" "cc $CFLAGS -I/usr/include/openblas test.c -lopenblas"]
{os = "fedora" | os = "centos" | os = "opensuse"}
["sh" "-exc" "cc $CFLAGS -I/usr/local/opt/openblas/include test.c
-L/usr/local/opt/openblas/lib -lopenblas"] {os = "darwin"}
["sh" "-exc" "cc $CFLAGS test.c -lopenblas"] {os != "fedora" & os !=
"centos" & os != "opensuse" & os != "darwin"}
]

(for example, maybe relying on pkg-config to find the library in
addition to the current test could work?)

If you can find a way to enrich those tests so that the test passes on
your machine (it detects your installation of openblas), and they keep
working for everyone else, you should feel free to submit a
pull-request on the OPAM repository.

To test changes to an opam fine locally, you should use "opam pin" as
documented here:
  https://opam.ocaml.org/doc/Usage.html#opam-pin

Note that one can move the detection logic out of the 'opam' file into
an external script, which can be convenient if the logic becomes
richer. You just have to store the script in the files/ subdirectory
of the package, and call it from the "build" rule. This is done for
example in the conf-libev package:
  https://github.com/ocaml/opam-repository/tree/master/packages/conf-libev/conf-libev.4-11/opam
  https://github.com/ocaml/opam-repository/blob/master/packages/conf-libev/conf-libev.4-11/files/build.sh
  https://github.com/ocaml/opam-repository/blob/master/packages/conf-libev/conf-libev.4-11/files/discover.ml

Finally: there is an interdependency between the way an external
library is detected in its conf-* packages, and the way depending
software finds it during its build. If a conf- file uses pkg-config,
the user package may also use pkg-config to select the build flag, so
merely extending the conf- package with non-pkg-config detection
(without hardening the depending packages) is not a satisfying
solution. If you extend the detection logic of conf-openblas, it would
be nice to check that the depending packages (in this case, I believe
only "owl") still build, or consider extending them with the same
logic.

Best

On Mon, Sep 10, 2018 at 10:09 AM Nicolas Ratier
<nicolas.ratier@femto-st.fr> wrote:
>
> Dear OCaml list,
>
> openblas is installed in my computer, but opam fail to find it.
> The opam message is: idon't find the file "cblas.h"(see 2)
>
> $ ls /usr/include/openblas/
> cblas.h  f77blas.h  lapacke_config.h  lapacke.h lapacke_mangling.h
> lapacke_utils.h  openblas_config.h
>
> I have the same problem with plplot (I need both to useowl)
>
> I work on:(Command: uname -mrs & lsb_release -ds)
> Linux 3.16.7-42-desktop x86_64
> "openSUSE 13.2 (Harlequin) (x86_64)"
> OCaml 4.06.1
> opam 1.2.2
>
> How to solve this ?
> I compile OpenBLAS from source (see 1)
> Is there a place to re-install OpenBLAS to be seen by Opam ?
>
> Thank you very much for your help
> Nicolas
>
> ==========================================================================
> 1
> ==========================================================================
>
>   OpenBLAS build complete. (BLAS CBLAS LAPACK LAPACKE)
>
>    OS               ... Linux
>    Architecture     ... x86_64
>    BINARY           ... 64bit
>    C compiler       ... GCC  (command line : gcc)
>    Fortran compiler ... GFORTRAN  (command line : gfortran)
>    Library Name     ... libopenblas_haswellp-r0.2.20.a (Multi threaded;
> Max num-threads is 12)
>
> To install the library, you can run "make
> PREFIX=/path/to/your/installation install".
>
> ===========================================================================
> 2
> ===========================================================================
> $ opam install conf-openblas
>
> =-=- Processing actions
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> [ERROR] The compilation of conf-openblas failed at "sh -exc cc $CFLAGS
> test.c -lopenblas".
>
> #=== ERROR while installing conf-openblas.0.2.0
> ===============================#
> # opam-version 1.2.2
> # os           linux
> # command      sh -exc cc $CFLAGS test.c -lopenblas
> # path /home/nicolas/.opam/4.06.1/build/conf-openblas.0.2.0
> # compiler     4.06.1
> # exit-code    1
> # env-file
> /home/nicolas/.opam/4.06.1/build/conf-openblas.0.2.0/conf-openblas-14498-dd682e.env
> # stdout-file
> /home/nicolas/.opam/4.06.1/build/conf-openblas.0.2.0/conf-openblas-14498-dd682e.out
> # stderr-file
> /home/nicolas/.opam/4.06.1/build/conf-openblas.0.2.0/conf-openblas-14498-dd682e.err
> ### stderr ###
> # + cc test.c -lopenblas
> # test.c:1:19: fatal error: cblas.h: Aucun fichier ou dossier de ce type
> #  #include <cblas.h>
> #                    ^
> # compilation terminated.
>
>
>
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