Do something sensible for items defined from :map/:com/... in :*usage!.

common/content/commands.js

@@ -453,7 +453,7 @@ const Commands = Module("commands", {
     _addCommand: function (args, replace) {
         if (!args[3])
             args[3] = {};
-        args[3].definedAt = Components.stack.caller.caller;
+        args[3].definedAt = commands.getCaller(Components.stack.caller.caller);
 
         let names = array.flatten(Command.parseSpecs(args[0]));
         dactyl.assert(!names.some(function (name) name in this._exMap && !this._exMap[name].user, this),
@@ -636,6 +636,22 @@ const Commands = Module("commands", {
         return this._exCommands.filter(function (cmd) cmd.user);
     },
 
+    /**
+     * Returns a frame object describing the currently executing
+     * command, if applicable, otherwise returns the passed frame.
+     *
+     * @param {nsIStackFrame} frame
+     */
+    getCaller: function (frame) {
+        if (io.sourcing)
+           return {
+                __proto__: frame,
+                filename: services.io.newFileURI(File(io.sourcing.file)).spec,
+                lineNumber: io.sourcing.line
+            };
+        return frame;
+    },
+
     /**
      * Returns true if a command invocation contains a URL referring to the
      * domain *host*.

common/content/mappings.js

@@ -140,7 +140,7 @@ const Mappings = Module("mappings", {
 
     _addMap: function (map) {
         let where = map.user ? this._user : this._main;
-        map.definedAt = Components.stack.caller.caller;
+        map.definedAt = commands.getCaller(Components.stack.caller.caller);
         map.modes.forEach(function (mode) {
             if (!(mode in where))
                 where[mode] = [];

common/content/options.js

@@ -642,7 +642,7 @@ const Options = Module("options", {
         if (!extraInfo)
             extraInfo = {};
 
-        extraInfo.definedAt = Components.stack.caller;
+        extraInfo.definedAt = commands.getCaller(Components.stack.caller);
 
         let name = names[0];
         if (name in this._optionMap) {

common/modules/template.jsm

@@ -289,6 +289,14 @@ const Template = Module("Template", {
     },
 
     usage: function usage(iter) {
+        function getPath(url) {
+            try {
+                return util.getFile(util.newURI(url)).path;
+            }
+            catch (e) {
+                return url;
+            }
+        }
         // <e4x>
         return <table>
             {
@@ -297,15 +305,12 @@ const Template = Module("Template", {
                     <td style="padding-right: 20px" highlight="Usage">{
                         let (name = item.name || item.names[0], frame = item.definedAt)
                             !frame ? name : /* Help... --Kris */
-                                let (url = frame.filename.replace(/.* -> /, ""))
+                                let (url = (frame.filename || "unknown").replace(/.* -> /, ""))
                                     <><span highlight="Title">{name}</span>&#xa0;
                                           <span highlight="LineInfo">
                                               Defined at&#xa0;<a xmlns:dactyl={NS} dactyl:command="buffer.viewSource"
                                                                  href={url} line={frame.lineNumber}
-                                                                 highlight="URL">{
-                                                  (util.getFile(util.newURI(url)) || { path: url }).path
-                                                    + ":" + frame.lineNumber
-                                                }</a>
+                                                                 highlight="URL">{ getPath(url) + ":" + frame.lineNumber }</a>
                                           </span>
                                         </>
                     }</td>