Provide ccache

[krlmlr]

and document usage for packaging. Will document usage for building R packages in https://github.com/r-windows/docs/blob/master/faq.md#readme.

IIUC the packages will be published to bintray when the PR is merged, so that the installation instructions work then?

Closes #143.

[jeroen]

You need to remove the dependency on "${MINGW_PACKAGE_PREFIX}-gcc-libs". In rtools everything is static, so we don't have separate libs packages.

R users are only supposed to build mingw packages, not msys runtime packages (this is a completely different build chain). So I think you can remove the last piece of the readme section.

[jeroen]

In your readme instructions, can you please use ${MINGW_PREFIX} for the PATH of hardcoding /mingw32 or /mingw64 ? See the other occurrences of ${MINGW_PREFIX} in that same file. That way the same instruction works for both.

Also we can install both packages at once like so:

pacman -S mingw-w64-{i686,x86_64}-ccache

So perhaps you can combine the instructions for mingw32 and mingw64.

[krlmlr]

Thanks, will do. Did you restart the build?

[krlmlr]

Tweaked in ffa23f7, not pushed here yet because I can't test the instructions because ccache isn't on bintray yet.

• Can we really install an i686 package from a mingw64 shell? Does this need to run in the msys2 shell?
• Does the modified PATH work?

Can we merge this PR and update the instructions after the built package is available?