Missing openblas package binary about conan-armadillo

[plusangel]

Firstly, thank for you time to write a detailed reply indicating and explaining all the possibilities to a newbie. Secondly, it worked like a charm. Great!

[darcamo]

Hello @plusangel,

Armadillo depends on the openblas and HDF5 libraries, which I have also created recipes for. These recipes are compiled for some compilers and some versions such that conan can just download the binary for the library as well as the headers. However, this does not include gcc version 7. For instance, run the command below

conan search "openblas/0.3.10@darcamo/stable" -r darcamo-bintray --table openblas.html

where you should replace darcamo-bintray by whatever name you choose for my repository. This will create a file called openblas.html that you can open in your browser to check for which platform (only Linux in my repository), compiler (including compiler version) and flags there are compiled binaries.

There are two ways you can proceed. One is to pass --build=openblas or --build=missing to the conan install command. This tells conan to compile binaries for each dependency that it has a recipe for but that don't have an already compiled binary for conan to just download. The installation will take more time because openblas will be compiled in your machine.

The other option is to tell conan to use openblas (and optionally HDF5) from your system. More specifically, I have added two options to the armadillo's recipe that you can use for this: use_system_blas and use_system_hdf5. The default value of both is False. If you set to True then armadillo's recipe will use BLAS/LAPACK and HDF5 from your system, instead of installing from conan recipes. I have only tested with ubuntu (long time ago) and Arch Linux (the one that I use). When these options are set to True conan will ask you the administrative password in order to run the package manager (either apt in case of ubuntu or pacman in case of Arch) to install BLAS, Lapack and HDF5. You can set them in your conanfile.txt as

[requires]
armadillo/10.1.0@darcamo/stable

[options]
armadillo:use_system_blas=True
armadillo:use_system_hdf5=True

[generators]
cmake

You can also pass these options directly in the command line with the conan install command as -o armadillo:use_system_blas=True

---

Since this issue is not a problem with the recipe I'll close the issue. In case you go with the "armadillo:use_system_[blas | hdf5] = True" approach and you don't use either ubuntu or Arch, it will fail. Pull requests are welcomed. All that is necessary is the value returned by conans.tools.os_info.linux_distro (in Python) and the name of the blas, lapack and hdf5 libraries in your distro.