[Nix-dev] substitute hell ?

[Sergey Mironov]

Hi again. I'm in trouble. Could anyone explain the situation:

We know that vlc package depends on a52dec. We have a substitution for vlc:

$ sudo nix-env -qas  'vlc' --system --out-path
--S  vlc-2.0.1  x86_64-linux
/nix/store/x332qx57qbak8rbmg4hhbjr5m7afn2df-vlc-2.0.1
--S  vlc-2.0.1  i686-linux
/nix/store/vwvz7hh1yc1bvjn6avylbzlgib8d2b60-vlc-2.0.1
--S  vlc-2.0.1  i686-linux
/nix/store/vwvz7hh1yc1bvjn6avylbzlgib8d2b60-vlc-2.0.1
(hm.. why are there two of them. ok, let it be so)

... but ...

$ sudo nix-env -qas  'a52dec' --system --out-path
---  a52dec-0.7.4  i686-linux
/nix/store/rzl2xsj45n3hy8bq8w31vifi49kbwxyg-a52dec-0.7.4

Threre is no substitute for a52dec! (And for some reason I can't find
a52dec job on a hydra website). How did hydra compile vlc without
building a52dec? If it actually did compile a52dec, then what is wrong
with it's substitution?