pkgcache internals

Gábor Csárdi

2024-09-13

Platforms

• get_cran_extension()
• get_all_package_dirs()
• async_repo_status()
• packages_make_target()
• packages_make_sources()
• cmc__get_cache_files()
• current_r_platform()
• default_platforms()

Windows

Windows is special, because the same repository is used for multiple architectures. Probably most people use 64 bit R on Windows, because that’s what RStudio starts by default. But we also need to make sure that people who need 32 bit R will have a way to install packages, without ruining the 64 bit installation.

Luckily, there are no packages on CRAN or Bioconductor currently that are 32 bit only. (There are a few that are 64 bit only.) In addition, 32 bit R currently installs the package for both architectures, when installing from source. (64 bit R-devel does the same currently, but this might change.)

In light of these, this is what we do:

• The default platform is x86_64-w64-mingw32 on 64 bit R from R 4.2. It is i386+x86_64-mingw32 on 64 bit R before R 4.2.
• The default platform is i386+x86_64-w64-mingw32 on 32 bit R.
• The windows platform name is an alias to i386+x86_64-w64-mingw32.
• When compiling a package from source, we’ll observe the requested platform name:
  • For x86_64-w64-mingw32 on 64 bit R, we compile 64 bit only.
  • For i386-w64-mingw32 on 64 bit R, we compile for both 32 bit and 64 bit. (There is probably no way to avoid using the current arch.)
  • For i386+x86_64-w64-mingw32 on 64 bit R, we compile for both 32 bit and 64.
  • For i386-w64-mingw32 on 32 bit R, we compile for both 32 bit and 64 bit. This is to avoid mistakenly messing up a 64 bit library.
  • For x86_64-w64-mingw32 on 32 bit R, we compile for both 32 bit and 64 bit. (There is probably no way to avoid using the current arch.)
  • For i386+x86_64-w64-mingw32 on 32 bit R, we compile for both 32 bit and 64 bit.

In summary, when compiling packages, we compile for both archs, except if we are in a 64 bit R session and the platform is x86_64-w64-mingw32.