Hi Pierre, I do not not if it related.
Currently, the option "--with-input" does not re-write the implicit inputs. Probably for good reasons. :-) For example, say I would like to have the version 3.4.3 of R (2017 old). This version is really old and had disappeared. Other said, it is older than the introduction of "inferior"s and so "guix time-machine" does not help (but that another story). At this point, it is not matter the GCC version that it is used to compile this R version. Well, it is not too complicated: git show cbe1314a7e:gnu/packages/statistics.scm > /tmp/stuff/old-stats.scm # edit old-stats.scm to tweak the modules guix build -L /tmp firstname.lastname@example.org Now, I would like to build the package r-rcpp at the version 1.0.3 which is introduced recently using the old R version 3.4.3. Well, the naive idea is: guix build -L /tmp --email@example.com r-rcpp but because r-minimal is an implicit inputs, it is not re-written. This behaviour is expected because the bag is really huge. To be convinced, try: "guix graph -t bag r-rcpp | dot -Tps > r-rcpp-bag.ps"... and wait... :-) >From a practical point of view, re-write any implicit inputs is touchy. And I do not know if the "parametrized package" is related or not at all -- I do not see real difference between re-compiling with this flags and re-compiling with this version -- but be able to recompile a matrix of combinaison would be really cool! All the best, simon