When investigating an issue with the latest Folly cbdep build, it was observed that changing manifest.cmake to a different folly version did not cause CBDownloadDeps et al to extract the newer version - it left the previous contents present.

For example, starting with a manifest.cmake containing VERSION v2022.05.23.00-couchbase-cb6:

DECLARE_DEP (folly VERSION v2022.05.23.00-couchbase-cb6 PLATFORMS amzn2 centos7 debian9 debian10 macosx suse12 suse15 ubuntu18.04 ubuntu20.04 windows)

Then changing back to VERSION v2022.05.23.00-couchbase-cb4, and re-running cmake shows the following output:

$ cmake ..

-- Checking exploded folly version v2022.05.23.00-couchbase against v2022.05.23.00-couchbase

-- Dependency 'folly (v2022.05.23.00-couchbase)' already downloaded

... and the contents of build/tlm/deps/folly.exploded is unchanged.

Poking into CBDownloadDeps, it appears that the function DECLARE_DEP assumes that only one hyphen will be present in the version string when extracting the build number. However this is not the case with folly (and prometheus-cpp), and hence the actual build number ends up getting ignored:

      # for V1, version is conventionally version-bld_num, so split it apart.

      # Occasionally there may be a version with no -, in which case the

      # bld_num is the empty string.

      STRING (REPLACE "-" ";" _dep_bits "${dep_VERSION}")

      LIST (POP_FRONT _dep_bits _dep_version _dep_bld_num)