lib/types: prioritise coercedType in coercedTo (#77691)

        tail' = tail ts;

      in foldl' either head' tail';

    # Either value of type `finalType` or `coercedType`, the latter is

    # Either value of type `coercedType` or `finalType`, the former is

    # converted to `finalType` using `coerceFunc`.

    coercedTo = coercedType: coerceFunc: finalType:

      assert lib.assertMsg (coercedType.getSubModules == null)

      mkOptionType rec {

        name = "coercedTo";

        description = "${finalType.description} or ${coercedType.description} convertible to it";

        check = x: finalType.check x || (coercedType.check x && finalType.check (coerceFunc x));

        check = x: (coercedType.check x && finalType.check (coerceFunc x)) || finalType.check x;

        merge = loc: defs:

          let

            coerceVal = val:

              if finalType.check val then val

              else coerceFunc val;

              if coercedType.check val then coerceFunc val

              else val;

          in finalType.merge loc (map (def: def // { value = coerceVal def.value; }) defs);

        emptyValue = finalType.emptyValue;

        getSubOptions = finalType.getSubOptions;