callCabal2nix doesn't work with musl-native

[nh2]

A follow-up for #43369.

@dtzWill @ElvishJerricco

I'm trying something like the following:

overlay.nix:

final:
  previous:
    with final.haskell.lib;
    {
      haskellPackages = previous.haskellPackages.override (old: {
        overrides = final.lib.composeExtensions (old.overrides or (_: _: {})) (self: super: {

          pretty-relative-time = self.callCabal2nix "pretty-relative-time" (final.fetchFromGitHub { ... }) {};

        });
      });
    }

(see #26561 (comment) for the interaction of nixpkgs overlays and haskellPackages.override)

used from https://github.com/nh2/static-haskell-nix/blob/627a8c5f86719531e1b1237aec4f5f85982cbd6c/survey/default.nix

by changing the first line to have nixpkgs ? (import <nixpkgs> { overlays = [ (import ./overlay.nix) ]; }).pkgsMusl.

Then I get:

% NIX_PATH=nixpkgs=https://github.com/NixOS/nixpkgs/archive/2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz nix-build --no-link survey/default.nix -A haskellPackages.pretty-relative-time
error: cannot coerce null to a string, at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:131:71

That error is in

nixpkgs/pkgs/development/haskell-modules/make-package-set.nix

Line 131 in 2c07921

LOCALE_ARCHIVE = pkgs.lib.optionalString buildPlatform.isLinux "${buildPackages.glibcLocales}/lib/locale/locale-archive";

Full trace:

% NIX_PATH=nixpkgs=https://github.com/NixOS/nixpkgs/archive/2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz nix-build --no-link survey/default.nix -A haskellPackages.pretty-relative-time --show-trace
error: while evaluating 'callCabal2nix' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:173:32, called from /home/niklas/src/haskell/intray/overlay.nix:39:38:
while evaluating 'overrideCabal' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/lib.nix:37:24, called from /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:183:8:
while evaluating 'callPackageKeepDeriver' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:156:33, called from /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:183:23:
while evaluating 'overrideCabal' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/lib.nix:37:24, called from /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:157:5:
while evaluating 'callPackage' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:115:22, called from /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:157:20:
while evaluating 'callPackageWithScope' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:75:37, called from /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:115:28:
while evaluating 'makeOverridable' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/lib/customisation.nix:72:24, called from /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:98:8:
while evaluating 'drvScope' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:88:18, called from /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/lib/customisation.nix:74:12:
while evaluating the attribute 'LOCALE_ARCHIVE' of the derivation 'cabal2nix-pretty-relative-time' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/stdenv/generic/make-derivation.nix:175:11:
while evaluating 'optionalString' at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/lib/strings.nix:138:26, called from /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:131:24:
cannot coerce null to a string, at /nix/store/w1fndb8swaamrf7amgjjvxfp12nifl2d-2c07921cff84dfb0b9e0f6c2d10ee2bfee6a85ac.tar.gz/pkgs/development/haskell-modules/make-package-set.nix:131:71

From IRC:

elvishjerricco> nh2: Yea the problem is that callCabal2nix relies on the glibcLocales thing. Not sure if it should... But if the pkgsMusl stuff doesn't provide that derivation, that would break callCabal2nix

@dtzWill Do you know what we could do about this glibcLocales?

[nh2]

From IRC:

dtz> nh2: I think I just never got that far previously--other nixpkgs references to using glibcLocales w/haskell on musl are conditional but this isn't
dtz> nh2: yeah so in generic-builder we do this:

nixpkgs/pkgs/development/haskell-modules/generic-builder.nix

Line 446 in e73a01f

LOCALE_ARCHIVE = optionalString (stdenv.hostPlatform.libc == "glibc") "${glibcLocales}/lib/locale/locale-archive";

nh2> comments must have been a bit out of fashion when LOCALE_ARCHIVE was added to haskellSrc2nix to fix ... something?
dtz> nh2: well it probably helps w/glibc! But IIRC musl has some other locale thing that I'm not even sure took off? MUSL_LOCPATH
nh2> dtz: I found the commit that added it: 69cda1a
nh2> it apparently fixed #5904

So I suspect that this is very related to some other thing I'm working on in GHC & co: That many Haskell build tools break when you don't force the encoding: commercialhaskell/stack#3988

{^_^}> [nixpkgs] @dtzWill opened pull request #43666 → haskell-modules: only include glibc locales when using glibc
dtz> nh2: well musl is utf8 by default :3 lol