The pip locker [sometimes created a URL without hash][1] to reflect that there was a local source.
This produced the following error when trying to evaluate that derivation:
… from call site
at /nix/store/qdzdi6qvrqxfqxhi3j70d5dsl9f5jpby-source/modules/dream2nix/pip/default.nix:86:28:
85| mkDerivation = {
86| src = l.mkDefault (fetchers.${metadata.sources.${config.name}.type} metadata.sources.${config.name});
| ^
87| doCheck = l.mkDefault false;
… while calling 'url'
at /nix/store/qdzdi6qvrqxfqxhi3j70d5dsl9f5jpby-source/modules/dream2nix/pip/default.nix:57:11:
56| fetchers = {
57| url = info: l.fetchurl {inherit (info) url sha256;};
| ^
58| git = info: config.deps.fetchgit {inherit (info) url sha256 rev;};
error: value is null while a string was expected
Of course, one cannot call `builtins.fetchurl` without a `sha256` argument.
Now, local dependencies are specified exactly like that in the lock file. Now, we'll fetch nothing when dealing with local dependencies.
Also, their evaluation when generating `preFixup` attribute is delayed until build time. This was a bigger problem due to the previous bug, but in any case it should still help to reduce evaluation overhead.
FWIW, sometimes local sources might not really exit in the derivation source tree until build time. For example, when building aggregated sources with meta-repo management tools such as Mr. Chef.
[1]: 40b65e4598/pkgs/fetchPipMetadata/src/fetch_pip_metadata/lock_file_from_report.py (L72C28-L72C28)
The suggested copy paste attribute path is often wrong as it depends on the individual repository setup that dream2nix doesn't control.
Instead now simply hint to `nix run` the .lock attribute
This allows updating the lock file via `nix run .#{package}.lock` instead of ` nix run .#{package}.config.lock.refresh`
This is better as it's shorter, and the keyword `lock` is widely understood to lock dependencies.
For many users not having a snapshot date is a valid use case.
Also many users will expect their lock file to be updated to the latest dependency versions via a nix run .#package.config.lock.refresh. so it can be the default behavior.
- nixpkgs-overrides are not lazy enough. They can lead to eval failures thrown in nixpkgs despite not being enabled. Therefore we better use the `import` as an enable mechanism instead of the `enable` option.
We keep the enable option to allow for users to disable the override module via mkForce
