The developPackage function generates a different hash every time

[mightybyte]

Issue description

Even when nothing changes in the package, when I use the developPackage function in my default.nix it rebuilds the package every time.

Pinging @shlevy

Steps to reproduce

git clone https://github.com/TaktInc/hadron.git
git checkout builds-with-nix
nix-build
nix-build

Technical details

• System: Darwin Kernel Version 15.6.0
• Nix version: nix-env (Nix) 1.11.13
• Nixpkgs version: 17.09pre111304.5328102325
• Sandboxing enabled: build-use-sandbox = false

[shlevy]

Thanks, will likely take a look this weekend.

[pbogdan]

Could this be related to the ./result symlink that nix-build leaves behind and src being set to ./. which would cause the source to change every time nix-build is invoked? @mightybyte do you see rebuilds if you manually remove ./result before re-running nix-build or run the builds with nix-build --no-out-link?

[mightybyte]

Yes, I tried this. If I remove the result symlink, then it gets the cached version. So I guess the developPackage function just has to be modified to filter that out (and/or maybe allow the user to filter out certain files).

[stale]

Thank you for your contributions.

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[cdepillabout]

haskellPackages.developPackage takes the directory as input as a root argument. If the user wants to filter out certain files before passing to developPackage, that is their responsibility. developPackage doesn't do any automatic filtering on its own.