anchor.diff:        });
         config = mkMerge [
           {
  -          warnings = optional (warn && fromOpt.isDefined)
  -            "The option `${showOption from}' defined in ${showFiles fromOpt.files} has been renamed to `${showOption to}'.";
  +          _module.assertions.${showOption from} = {
  +            enable = mkDefault (warn && fromOpt.isDefined);
  +            type = "warning";
  +            message = "The option `${showOption from}' defined in ${showFiles fromOpt.files} has been renamed to `${showOption to}'.";
  +          };
           }
           (if withPriority
             then mkAliasAndWrapDefsWithPriority (setAttrByPath to) fromOpt
  
positive.code:       })) from);
  
        config = {
          warnings = filter (x: x != "") (map (f:
            let val = getAttrFromPath f config;
                opt = getAttrFromPath f options;
            in
            optionalString
              (val != "_mkMergedOptionModule")
              "The option `${showOption f}' defined in ${showFiles opt.files} has been changed to `${showOption to}' that has a different type. Please read `${showOption to}' documentation and update your configuration accordingly."
          ) from);
        } // setAttrByPath to (mkMerge
               (optional
                 (any (f: (getAttrFromPath f config) != "_mkMergedOptionModule") from)
  
negative.code:         visible = false;
          apply = x: throw "The option `${showOption optionName}' can no longer be used since it's been removed. ${replacementInstructions}";
        });
        config._module.assertions =
          let opt = getAttrFromPath optionName options; in {
          ${showOption optionName} = {
            enable = mkDefault opt.isDefined;
            message = ''
              The option definition `${showOption optionName}' in ${showFiles opt.files} no longer has any effect; please remove it.
              ${replacementInstructions}
            '';
          };
        };
      };
  
    /* Return a module that causes a warning to be shown if the
  