commercialhaskell/stack

Nix integration should use GC roots

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#3,479 opened on Oct 9, 2017

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component: nixhelp wanted

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Description

Usual scenario:

  1. build stack project with Nix
  2. sometime later you run nix-store --gc or nix-collect-garbage
  3. you run into following error:
/home/user/.stack/setup-exe-cache/x86_64-linux-nix/Cabal-simple_mPHDZzAJ_1.24.2.0_ghc-8.0.2: streamingProcess: runInteractiveProcess: exec: does not exist (No such file or directory)

This means that nix libraries that the file was compiled with are missing from nix store.

Best way to prevent this is to create Nix GC roots. Also stack could double check that those libraries are still intact.

Contributor guide

Research direction
Examine the Nix integration in Stack, understand how GC roots work in Nix, and implement a mechanism to create GC roots for Stack's Nix dependencies to prevent garbage collection from removing them. Also add a check to verify library integrity.
Tech stack
haskell
Domain
build system
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
HaskellNix
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40