[Nix-dev] Using ccache without changing stdenv hash?

[Wout Mertens]

I don't follow. It's a cache, so it always returns the same output for a
given set of inputs (compiler version, source files, preprocessor
settings). Its presence should be undetectable.

The only impurity is that time taken to compile is dependent on previous
compiles, no?

However, it is still useful for development but not if using it means
rebuilding the world on your laptop... So I'd like to at least offer the
option for development.

Wout.

On Tue Dec 09 2014 at 6:32:04 PM Shea Levy <shea at shealevy.com> wrote:

> ccache is impure and thus should not be used for hydra.
>
> On Dec 9, 2014, at 5:28 PM, Wout Mertens <wout.mertens at gmail.com> wrote:
>
> Hi all,
>
> there is some support for ccache in the tree but nothing in the way of
> documentation. I gave it a shot, see
> https://github.com/NixOS/nixpkgs/issues/2387#issuecomment-66215017, and
> it seems to work however it also changes the hash of stdenv.
>
> Is there a way to change stdenv so that ccache can be turned on or off
> without causing rebuilds?
>
> I'm convinced that this would be a major boon for Hydra, which probably
> spends a lot of time compiling the same C/C++ files with the same
> preprocessed output. Likewise for developing expressions.
>
> Wout.
>
> _______________________________________________
> nix-dev mailing list
> nix-dev at lists.science.uu.nl
> http://lists.science.uu.nl/mailman/listinfo/nix-dev
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.science.uu.nl/pipermail/nix-dev/attachments/20141209/6de26265/attachment.html