What it does: line and column level *declaration* position information:
$ nix repl .
nix-repl> :p nixosConfigurations.micro.options.environment.systemPackages.declarationPositions
[ { column = 7; file = "/nix/store/24aj3k7fgqv3ly7qkbf98qvphasrw9nb-source/nixos/modules/config/system-path.nix"; line = 63; } ]
Use cases:
- ctags over NixOS options, as will be presented at NixCon 2023 ;)
- improving the documentation pages to go to the exact line of the
declarations.
Related work:
- https://github.com/NixOS/nixpkgs/pull/65024
This one does it for all *definitions* rather than declarations, and
it was not followed through with due to performance worries.
- https://github.com/NixOS/nixpkgs/pull/208173
The basis for this change. This change is just a rebase of that one.
I split it out to add the capability before adding users of it, in
order to simplify review. However, the ctags script in there is a
sample user of this feature.
Benchmarks: conducted by evaluating my own reasonably complex NixOS
configuration with the command:
`hyperfine -S none -w 1 -- "nix eval .#nixosConfigurations.snowflake.config.system.build.toplevel.outPath"`
```
Benchmark 1: nix eval .#nixosConfigurations.snowflake.config.system.build.toplevel.outPath
Time (mean ± σ): 8.971 s ± 0.254 s [User: 5.872 s, System: 1.388 s]
Range (min … max): 8.574 s … 9.327 s 10 runs
Benchmark 1: nix eval .#nixosConfigurations.snowflake.config.system.build.toplevel.outPath
Time (mean ± σ): 8.766 s ± 0.160 s [User: 5.873 s, System: 1.346 s]
Range (min … max): 8.496 s … 9.033 s 10 runs
```
Summary of results: it seems to be in the noise, this does not cause any
visible regression in times.
mkOption does not require a `type` argument and does not set the
resulting attribute if it is not given. Consequently, we need to be
prepared to merge options that have no type information.
Having the current bash hash present in the nixpkgs tree makes Nix
detect bash as a runtime dependency of nixpkgs, which in turns messes up
`fetchFromGitHub` due to https://github.com/NixOS/nix/issues/6660
This will let us make assertions involving _module.args.pkgs, which
is not an option but a value attribute, and therefore doesn't have
its own highestPrio to inspect. The new function gives us that info.
This is to avoid stealing keys from submodules. `class` might be
common enough that reinterpreting existing `class` attributes in
configurations as a declaration leads to fairly widespread problems.
This is appears to be a fairly common mistake for beginners who want
to build larger things from the system configurations, such as NixOps
networks, etc. Further explanation seems appropriate.
This makes the following work
disabledModules = [ foo.nixosModules.bar ];
even if `bar` is not a path, but rather a module such as
{ key = "/path/to/foo#nixosModules.bar"; config = ...; }
By supporting this, the user will often be able to use the same syntax
for both importing and disabling a module. This is becoming more relevant
because flakes promote the use of attributes to reference modules. Not
all of these modules in flake attributes will be identifiable, but with
the help of a framework such as flake-parts, these attributes can be
guaranteed to be identifiable (by outPath + attribute path).
Add trace items that provide context for a failed definition that
can not be caught within the Nix language.
This also adds a test for the `tryEval` behavior of `showDefs`.
The motivation is to have a single identifier for that. Useful for the
next commit where I'll try to escape option-parts correctly (options can
be any kind of strings, but unless these are Nix identifiers, they must
be quoted).
Since `<function body>` (or `<name>`/`*`) are special identifiers in
error messages and the manual, we need a unique way to mark an option
part as function call because these are not to be quoted.
This is particularly useful for disabling modules defined in a flake.
Example:
disabledModules = [ "${flake}/modules/mymodule.nix" ];
Previously, absolute string paths were internally prepended with `modulesPath`,
which caused the module filtering to fail.
`m` must always be an attrset at this point. It is basically always
evaluated. This will make it throw when any of the attrs is accessed,
rather than just `config`. We assume that this will improve the error
message in more scenarios.
