Add cargo llvm-cov to flake devshell

[nothingmuch]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 12938871114

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 78.541%

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Totals
Change from base Build 12933041269:	0.0%
Covered Lines:	3638
Relevant Lines:	4632

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💛 - Coveralls

[DanGould]

When I tried to test output says cargo-llvm-cov-0.6.14 is marked as broken. is that OK?

Details

payjoin % nix develop
error:
       … while calling the 'derivationStrict' builtin
     at /builtin/derivation.nix:9:12: (source not available)

   … while evaluating derivation 'nix-shell'
     whose name attribute is located at /nix/store/8vz84mqgnm1gz5yk7hgnnb5gir5hjxas-source/pkgs/stdenv/generic/make-derivation.nix:375:7

   … while evaluating attribute 'nativeBuildInputs' of derivation 'nix-shell'

     at /nix/store/8vz84mqgnm1gz5yk7hgnnb5gir5hjxas-source/pkgs/stdenv/generic/make-derivation.nix:419:7:

      418|       depsBuildBuild              = elemAt (elemAt dependencies 0) 0;
      419|       nativeBuildInputs           = elemAt (elemAt dependencies 0) 1;
         |       ^
      420|       depsBuildTarget             = elemAt (elemAt dependencies 0) 2;

   error: Package ‘cargo-llvm-cov-0.6.14’ in /nix/store/8vz84mqgnm1gz5yk7hgnnb5gir5hjxas-source/pkgs/by-name/ca/cargo-llvm-cov/package.nix:85 is marked as broken, refusing to evaluate.

   a) To temporarily allow broken packages, you can use an environment variable
      for a single invocation of the nix tools.

        $ export NIXPKGS_ALLOW_BROKEN=1

      Note: When using `nix shell`, `nix build`, `nix develop`, etc with a flake,
            then pass `--impure` in order to allow use of environment variables.

   b) For `nixos-rebuild` you can set
     { nixpkgs.config.allowBroken = true; }
   in configuration.nix to override this.

   c) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
     { allowBroken = true; }
   to ~/.config/nixpkgs/config.nix.

[nothingmuch]

see NixOS/nixpkgs#351574 and its discussion

i guess we can make it conditional, and skip it on mac

[DanGould]

optional and omitted on mac is a workable solution

[DanGould]

See how optional compilation is configured in mutiny-node's flake

[nothingmuch]

i only added the optionality to the cargo-llvm-cov package (not the associated rust toolchain component), and tested that the devshell is no longer broken on a mac

[DanGould]

tACK 5654ea8 by running nix develop on MacOS