nmattia/niv

"Could not read the output of 'nix-prefetch-url'. This is a bug."

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#330 opened on Sep 6, 2021

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Description

When trying out Niv and following the example from the readme to add GHC:

$ niv add ghc   \
    -v 8.4.3    \
    -t 'https://downloads.haskell.org/~ghc/<version>/ghc-<version>-i386-deb8-linux.tar.xz'

But instead using the latest ghc version (9.0.1 as of writing), I get the following error:

$ niv add ghc -v 9.0.1 -t 'https://downloads.haskell.org/~ghc/<version>/ghc-<version>-i386-deb8-linux.tar.xz'
Adding package ghc
  FATAL: Could not read the output of 'nix-prefetch-url'. This is a bug. Please create a
  ticket:
  
    https://github.com/nmattia/niv/issues/new
  
  Thanks! I'll buy you a beer.
  command: 
  nix-prefetch-urlhttps://downloads.haskell.org/~ghc/9.0.1/ghc-9.0.1-i386-deb8-linux.tar.xz --name ghc-9.0.1-i386-deb8-linux.tar.xz
  stdout: 
  
  stderr: 
  error: unable to download 'https://downloads.haskell.org/~ghc/9.0.1/ghc-9.0.1-i386-deb8-linux.tar.xz': HTTP error 404
  
  FATAL: One or more packages failed to update:
  ghc: ExitFailure 1
ERROR: ExitFailure 1

The solution is quite simple, simply change deb8 to deb9, as no deb8 file exists. However, the error asked me to post this so I did.

The command that does work:

niv add ghc -v 9.0.1 -t 'https://downloads.haskell.org/~ghc/<version>/ghc-<version>-i386-deb9-linux.tar.xz'

I got the same problem when I tried version 8.10.6, for the same reason and with same fix.

Contributor guide

Tech stack
None
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.
1
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
None
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
90
Research direction
Look in the repository for the default URL template used when adding a package. Search for the string 'deb8' in the source code to locate where the GHC URL pattern is defined. The fix is to change 'deb8' to 'deb9' or to make the template more flexible to accommodate different Debian versions. Also check if there are other similar hardcoded patterns that might need updating.