dotnet: infrastructure improvements (#336824)

## Generating and updating NuGet dependencies {#generating-and-updating-nuget-dependencies}

When writing a new expression, you can use the generated `fetch-deps` script to initialise the lockfile.

After creating a blank `deps.nix` and pointing `nugetDeps` to it,

After setting `nugetDeps` to the desired location of the lockfile (e.g. `./deps.nix`),

build the script with `nix-build -A package.fetch-deps` and then run the result.

(When the root attr is your package, it's simply `nix-build -A fetch-deps`.)

  infrastructure. Regular updates should be done through the individual packages

  update scripts.

 */

{ startWith ? null }:

let

  pkgs = import ../.. { config.allowAliases = false; };

  packagesWith = cond: pkgs:

    let

      packagesWithInner = attrs:

        lib.unique (

        lib.concatLists (

          lib.mapAttrsToList (name: elem:

            let

                    if lib.isAttrs value && (value.recurseForDerivations or false || value.recurseForRelease or false) then

                      packagesWithInner value

                    else []

                else []) attrs));

              else []) attrs);

    in

      packagesWithInner pkgs;

  packages =

    packagesWith (pkgs: pkgs ? fetch-deps) pkgs;

  packages = lib.unique

    (lib.filter (p:

      (builtins.tryEval p.outPath).success ||

      builtins.trace "warning: skipping ${p.name} because it failed to evaluate" false)

    ((pkgs: (lib.drop (lib.lists.findFirstIndex (p: p.name == startWith) 0 pkgs) pkgs))

    (packagesWith (p: p ? fetch-deps) pkgs)));

  helpText = ''

    Please run:

  dotnet-sdk = dotnetCorePackages.sdk_7_0;

  dotnet-runtime = dotnetCorePackages.runtime_7_0;

  # [...]/Microsoft.NET.Sdk.targets(157,5): error MSB4018: The "GenerateDepsFile" task failed unexpectedly. [[...]/OpenUtau.Core.csproj]

  # [...]/Microsoft.NET.Sdk.targets(157,5): error MSB4018: System.IO.IOException: The process cannot access the file '[...]/OpenUtau.Core.deps.json' because it is being used by another process. [[...]/OpenUtau.Core.csproj]

  enableParallelBuilding = false;

  projectFile = "OpenUtau.sln";

  nugetDeps = ./deps.nix;

{

  writeShellScript,

  runtimeShell,

  nix,

  lib,

  substituteAll,

  nuget-to-nix,

  cacert,

  fetchNupkg,

  callPackage,

}:

{

  nugetDeps,

  overrideFetchAttrs ? x: { },

}:

fnOrAttrs: finalAttrs:

let

  attrs = if builtins.isFunction fnOrAttrs then fnOrAttrs finalAttrs else fnOrAttrs;

  deps =

    if (nugetDeps != null) then

      if lib.isDerivation nugetDeps then

        [ nugetDeps ]

      else if lib.isList nugetDeps then

        nugetDeps

      else

        assert (lib.isPath nugetDeps);

        callPackage nugetDeps { fetchNuGet = fetchNupkg; }

    else

      [ ];

  finalPackage = finalAttrs.finalPackage;

in

attrs

// {

  buildInputs = attrs.buildInputs or [ ] ++ deps;

  passthru =

    attrs.passthru or { }

    // {

      nugetDeps = deps;

    }

    // lib.optionalAttrs (nugetDeps == null || lib.isPath nugetDeps) rec {

      fetch-drv =

        let

          pkg' = finalPackage.overrideAttrs (old: {

            buildInputs = attrs.buildInputs or [ ];

            nativeBuildInputs = old.nativeBuildInputs or [ ] ++ [ cacert ];

            keepNugetConfig = true;

            dontBuild = true;

            doCheck = false;

            dontInstall = true;

            doInstallCheck = false;

            dontFixup = true;

            doDist = false;

          });

        in

        pkg'.overrideAttrs overrideFetchAttrs;

      fetch-deps =

        let

          drv = builtins.unsafeDiscardOutputDependency fetch-drv.drvPath;

          innerScript = substituteAll {

            src = ./fetch-deps.sh;

            isExecutable = true;

            inherit cacert;

            nugetToNix = nuget-to-nix;

          };

          defaultDepsFile =

            # Wire in the depsFile such that running the script with no args

            # runs it agains the correct deps file by default.

            # Note that toString is necessary here as it results in the path at

            # eval time (i.e. to the file in your local Nixpkgs checkout) rather

            # than the Nix store path of the path after it's been imported.

            if lib.isPath nugetDeps && !lib.isStorePath nugetDeps then

              toString nugetDeps

            else

              ''$(mktemp -t "${finalAttrs.pname or finalPackage.name}-deps-XXXXXX.nix")'';

        in

        writeShellScript "${finalPackage.name}-fetch-deps" ''

          set -eu

          echo 'fetching dependencies for' ${lib.escapeShellArg finalPackage.name} >&2

          # this needs to be before TMPDIR is changed, so the output isn't deleted

          # if it uses mktemp

          depsFile=$(realpath "''${1:-${lib.escapeShellArg defaultDepsFile}}")

          export TMPDIR

          TMPDIR=$(mktemp -d -t fetch-deps-${lib.escapeShellArg finalPackage.name}.XXXXXX)

          trap 'chmod -R +w "$TMPDIR" && rm -fr "$TMPDIR"' EXIT

          export NUGET_HTTP_CACHE_PATH=''${NUGET_HTTP_CACHE_PATH-~/.local/share/NuGet/v3-cache}

          HOME=$TMPDIR/home

          mkdir "$HOME"

          cd "$TMPDIR"

          NIX_BUILD_SHELL=${lib.escapeShellArg runtimeShell} ${nix}/bin/nix-shell \

            --pure --keep NUGET_HTTP_CACHE_PATH --run 'source '${lib.escapeShellArg innerScript}' '"''${depsFile@Q}" "${drv}"

        '';

    };

}

set -e

genericBuild

(

    echo -e "# This file was automatically generated by passthru.fetch-deps.\n# Please dont edit it manually, your changes might get overwritten!\n"

    @nugetToNix@/bin/nuget-to-nix "${NUGET_PACKAGES%/}"

) > deps.nix

mv deps.nix "$1"

echo "Succesfully wrote lockfile to $1"