niv doesn't build with latest nixpkgs

YorikSar commented 3 years ago

I'm trying out niv for my repo and when I try to use nix version from sources.nix created by niv init, I'm getting following build failure:

src/Niv/Update.hs:299:3: error: [-Woverlapping-patterns, -Werror=overlapping-patterns]
    Pattern match is redundant
    In a case alternative: _ -> ...
    |
299 |   _ -> Just $ pure T.empty
    |   ^^^^^^^^^^^^^^^^^^^^^^^^

Steps to reproduce:

in empty dir, run niv init

change nix/sources.json to match:

{
"niv": {
    "branch": "master",
    "description": "Easy dependency management for Nix projects",
    "homepage": "https://github.com/nmattia/niv",
    "owner": "nmattia",
    "repo": "niv",
    "rev": "ba57d5a29b4e0f2085917010380ef3ddc3cf380f",
    "sha256": "1kpsvc53x821cmjg1khvp1nz7906gczq8mp83664cr15h94sh8i4",
    "type": "tarball",
    "url": "https://github.com/nmattia/niv/archive/ba57d5a29b4e0f2085917010380ef3ddc3cf380f.tar.gz",
    "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
},
"nixpkgs": {
    "branch": "master",
    "description": "Nix Packages collection",
    "homepage": "",
    "owner": "NixOS",
    "repo": "nixpkgs",
    "rev": "272744825d28f9cea96fe77fe685c8ba2af8eb12",
    "sha256": "0sn0bcdlp8zm1jca73wcvm7p6miq6gp81kjkcl7b9gbwzcnxac7l",
    "type": "tarball",
    "url": "https://github.com/NixOS/nixpkgs/archive/272744825d28f9cea96fe77fe685c8ba2af8eb12.tar.gz",
    "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
}
}

add test.nix with following contents:

let
sources = import ./nix/sources.nix;
pkgs = import sources.nixpkgs {};
niv = import sources.niv { inherit pkgs; };
in
niv.niv

run nix-build test.nix

Note that pkgs.niv works fine, even though it's built with the same compiler and the line in question is present in 0.2.18 tag used there.

zimbatm commented 3 years ago

it's probably related to https://discourse.nixos.org/t/new-ghc-default-version-8-10-2-package-versions-now-from-stackage-nightly/10117

YorikSar commented 3 years ago

Yes, but it works fine in Nixpkgs, that's why I'm surprised it doesn't work directly like this.

nmattia commented 3 years ago

Hi! Thanks for reporting. Just came back from holidays, I'm hoping #298 will fix the issue, though looks like there might be a few hurdles.

YorikSar commented 3 years ago

@nmattia Wow, that's a huge diff. That's for looking into this.

nmattia commented 3 years ago

Please thank @lrworth instead!

nmattia / niv

niv doesn't build with latest nixpkgs #297