Hi!
zimoun <zimon.toutoune@gmail.com> skribis:
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> On Wed, 23 Sep 2020 at 18:23, Ludovic Courtès <ludo@gnu.org> wrote:>>> Concretely, the following commands had no effect thus far:>>>> guix build python-itsdangerous --with-input=python=python2>> guix build hello --with-input=gcc=gcc-toolchain@10>>>> In both cases, this is because the input we want to change is>> an implicit input. This patch set fixes that, and it fixes>> <https://issues.guix.gnu.org/42156> as a side effect.>> Awesome!>> Therefore, 'package-with-explicit-python' & co. are becoming obsolete> (or almost), right?
Good question, we’d have to check on a case-by-case basis.‘package-input-rewriting’ is coarser-grain: it can potentially rewrite‘python’ dependencies deeper in the graph than‘package-with-explicit-python’.
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>> This opens new possibilities. ‘--with-input=python=python2’ is one>> of them, but ‘--with-input=gcc=gcc-toolchain@10’ is not (it fails>> to build for obscure reasons that I’ll fix in ‘core-updates’, and>> it rebuilds the world anyway, which is not practical). Another>> Rebuilding the world, maybe. :-) It is interesting in the HPC context> where one would like use an "optimized" compiler, isn't?
Like I wrote, ‘--with-input=gcc=gcc-toolchain@10’ (or similar) isn’tpractical: you’d have to rebuild the world.
What I envision for the use case where you want to build a specificpackage set with a different toolchain is to have a‘--with-toolchain=PACKAGE=TOOLCHAIN’ option. That would rebuild PACKAGEwith TOOLCHAIN. Then it would either rebuild all its dependents (as per‘--with-input’) or graft the rebuilt package (as per ‘--with-graft’).The latter may not always be a viable option though, so I don’t know.
In fact I think it would be nice if the graft vs. rebuild choice couldbe made independently for all the transformation options.
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> Thank you. I will give it a try for my use cases. :-)
Awesome, let me know how it goes!
Thank you,Ludo’.