nix develop quite slow on macOS 15.0

[stevalkr]

Describe the bug

I upgraded to macOS 15.0 and fixed the uid issue #10892 by setting NIX_FIRST_BUILD_UID="400". It works but I found nix develop way slower than before, takes me ~3s to evaluate. Here is my nix.conf

build-users-group = nixbld
keep-outputs = true
keep-derivations = true
extra-experimental-features = nix-command flakes

Steps To Reproduce

1. run nix develop the second time with any flake.nix

Expected behavior

Everything is cached, so it should be as fast as before

nix-env --version output

nix-env (Nix) 2.23.3

Priorities

Add 👍 to issues you find important.

[roberth]

This could be

• Eval cache: fix cache regressions #11086

Could you try with master, e.g. nix shell nix?

[stevalkr]

~> /nix/store/0j87742gdckpk41cjdcxfhylgmyszjvb-nix-2.24.0pre20240728_0e151bc/bin/nix --version
nix (Nix) 2.24.0pre20240728_0e151bc

Thank you, I tested two flakes that need around 4 seconds to evaluate with nix_2.23.3. It becomes faster on the third run when I use nix_2.24.0pre develop. Could you explain why it’s not cached after the first run and requires two runs to do the job?

And one thing off topic, nix shell nix doesn't replace nix for me, I have to find the path manually, so what's the proper way to have nix on master branch? Great thanks anyway :D