[Nix-dev] NIX_ENFORCE_NO_NATIVE

[Vladimír Čunát]

On 06/09/2016 10:17 AM, Andreas Herrmann wrote:
>> IIRC its' conditioned on $NIX_ENFORCE_NO_NATIVE exactly in order
>> not to be filtered out when run outside a nix builder. IMO that's a
>> good default. Hydra isn't the only reason; many devs use remote
>> builds or nix-copy-closure.
> How would you nix-copy-closure something that was compiled outside of
> nix? Maybe, we're talking about different things. What I mean is
> using a GCC that was built by Nix directly on the command-line

You seem to have missed my main point, so let me be more clear.

1) Outside nix builder $NIX_ENFORCE_NO_NATIVE is *not* active unless you
explicitly set it, i.e. -march=native *is* passed to the underlying GCC.
I re-tested that now by reading code and using (2).

2) If you set NIX_DEBUG=1 those omission won't be silent:
$ env NIX_ENFORCE_NO_NATIVE=1 NIX_DEBUG=1 g++ [...]
skipping impure path -march=native
[...]

(Yes, in this case it's not very friendly to call it a path.)

--Vladimir

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