mergeOptionDecls

lib.mergeOptionDecls

Docs pulled from | This Revision | 1 day ago

Nixpkgs manual

Merge multiple option declarations into a single declaration. In general, there should be only one declaration of each option. The exception is the ‘options’ attribute, which specifies sub-options. These can be specified multiple times to allow one module to add sub-options to an option declared somewhere else (e.g. multiple modules define sub-options for ‘fileSystems’).

'loc' is the list of attribute names where the option is located.

'opts' is a list of modules. Each module has an options attribute which correspond to the definition of 'loc' in 'opt.file'.

Inputs

loc: 1. Function argument
opts: 2. Function argument

Noogle detected

Aliases

lib.modules.mergeOptionDecls

Implementation

The following is the current implementation of this function.

mergeOptionDecls =
    loc: opts:
    foldl'
      (
        res: opt:
        let
          t = res.type;
          t' = opt.options.type;
          mergedType = t.typeMerge t'.functor;
          typesMergeable = mergedType != null;

          typeSet =
            if opt.options ? type && res ? type then
              if typesMergeable then
                {
                  type = mergedType;
                }
              else
                # Keep in sync with the same error below!
                throw
                  "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
            else
              { };

          bothHave = k: opt.options ? ${k} && res ? ${k};
        in
        if bothHave "default" || bothHave "example" || bothHave "description" || bothHave "apply" then
          # Keep in sync with the same error above!
          throw
            "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
        else
          let
            getSubModules = opt.options.type.getSubModules or null;
            submodules =
              if getSubModules != null then
                map (setDefaultModuleLocation opt._file) getSubModules ++ res.options
              else
                res.options;
          in
          opt.options
          // res
          // {
            declarations = res.declarations ++ [ opt._file ];
            # In the case of modules that are generated dynamically, we won't
            # have exact declaration lines; fall back to just the file being
            # evaluated.
            declarationPositions =
              res.declarationPositions
              ++ (
                if opt.pos != null then
                  [ opt.pos ]
                else
                  [
                    {
                      file = opt._file;
                      line = null;
                      column = null;
                    }
                  ]
              );
            options = submodules;
          }
          // typeSet
      )
      {
        inherit loc;
        declarations = [ ];
        declarationPositions = [ ];
        options = [ ];
      }
      opts;