Compiler selection

gistfile1.txt

ceph-build and gcc:

for pbuilder systems (debian, ubuntu):

0) the jenkins jobs include a number of scripts in order:
- validate_deb just checks if it's a debian build and exits otherwise
- build_utils.sh loads a bunch of library functions
- setup_deb sets up envvars, chacra dirs/config, etc.
- setup_pbuilder calls build_utils' setup_pbuilder sets up pbuilder
- build_deb calls build_utils' build_debs()


setup_pbuilder:

1) is always called with use_gcc as $1, which causes it to..

2) create a hookdir for when pbuilder runs, and install D04install-updates-repo, which (only for ubuntu):
   - enableds $DIST-{updates,backports,security} for Ubuntu
   - does apt-get update and apt install gnupg
 Note that, like both hook scripts, these run at pbuilder time, not at
 setup_pbuilder time

3) calls setup_pbuilder_for_ppa, which, confusingly, installs either

  - use_ppa()=false: D10update-gcc-alternatives, which uses the gcc
  shipped by the distro (for trusty-jammy), recorded in the script
  (up to gcc11 for jammy), or

  - use_ppa()=true: D05install-new-gcc to set up the 'ubuntu-toolchain'
  repos (only for ceph >17 and ubuntu focal)

build_debs() includes CEPH_EXTRA_CMAKE_ARGS when launching pbuilder, which
can also affect compiler choice.