[Nix-dev] How do you work on big packages?

[Will Dietz]

Just to add to this, something I haven't seen neatly documented but I
personally find very helpful (if a bit rough) is to run "genericBuild"
from within nix-shell, which will run the phases from the
derivation... and usually fail to install during installPhase.  I
often start this and then just interrupt it during the build so I can
poke at the source or config.log or whatever.

Anyway, it is an easy way to say "just do what nix-build does" for
unknown derivations.  Doesn't let you re-use the bits and install into
the nix store, but usually that's much less of an issue--once I have a
thing working I don't mind rebuilding (in fact, it's /good/ to rebuild
from scratch before saying "ship it") one final time.

~Will

PS: nix-shell doesn't set NIX_BUILD_CORES so I often do something like
'NIX_BUILD_CORES=8 genericBuild' (or whatever)

On Fri, Mar 17, 2017 at 2:26 PM, Profpatsch <mail at profpatsch.de> wrote:
> On 17-03-17 06:04pm, Volth wrote:
>> "nix-shell" would be a super option here if it could handle
>> "installPhase" (this seems easy to fix) and .nix files less trivial
>> than "hello.nix" (this seems not easy to fix; for example "nix-shell
>> '<nixpkgs>' -A linux_4_4" has no "configurePhase", and there are
>> similar problems with almost every of the big projects; nix-shell
>> launches "make" when "nix-build" launches "cmake" or vice-versa, etc)
>
> That’s a pretty common stumbling block.
>
> If someone defines his own `installPhase` for example,
> the `installPhase` shell function is just the standard
> stdenv `installPhase`. What you want to call is rather
> the contents of `$installPhase` (the variable), since
> that contains the phase you defined in `mkDerivation`.
>
> nix-shell
> $ unpackPhase
> unpacking …
> $ configurePhase
> configuring …
> $ buildPhase
> …
> $ $installPhase
> running your installPhase
>
>
> There is not much abstraction. Every nix attribute within
> `derivation` (and by extension `mkDerivation`) will end up
> as a bash shell variable in your shell (and your build env).
>
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