Fix for issue 23432 - Get the correct receiver in noSuchMethod stubs.

pkg/compiler/lib/src/js_emitter/old_emitter/nsm_emitter.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js.js_emitter;
 
 class NsmEmitter extends CodeEmitterHelper {
   final List<Selector> trivialNsmHandlers = <Selector>[];
 
   /// If this is true then we can generate the noSuchMethod handlers at startup
@@ skipping 260 matching lines @@
            'diffEncoding': js.string('$diffEncoding')}));
       if (!minify) {
         statements.add(js.statement('var longNames = #longs.split(",")',
                 {'longs': js.string(longs.join(','))}));
       }
       statements.add(js.statement(
           'if (objectClassObject instanceof Array)'
           '  objectClassObject = objectClassObject[1];'));
     }
 
-    List<jsAst.Expression> sliceOffsetArguments =
+    dynamic isIntercepted = // jsAst.Expression or bool.

[floitsch, 2015/06/19 21:22:15]

firstNormalSelector != 0 &&
(firstNormalSelector == shorts.length || js('j < #',
js.number(firstNormalSelector))

?

[sra1, 2015/06/22 20:17:00]

You can't use || to pick the jsAst.  || is bool*bool->bool

         firstNormalSelector == 0
-        ? []
-        : (firstNormalSelector == shorts.length
-            ? [js.number(1)]
-            : [js('(j < #) ? 1 : 0', js.number(firstNormalSelector))]);
-
-    var sliceOffsetParams = sliceOffsetArguments.isEmpty ? [] : ['sliceOffset'];
+        ? false
+        : firstNormalSelector == shorts.length
+            ? true
+            : js('j < #', js.number(firstNormalSelector));
 
     statements.add(js.statement('''
       // If we are loading a deferred library the object class will not be in
       // the collectedClasses so objectClassObject is undefined, and we skip
       // setting up the names.
       if (objectClassObject) {
         for (var j = 0; j < shortNames.length; j++) {
           var type = 0;
-          var short = shortNames[j];
-          if (short[0] == "${namer.getterPrefix[0]}") type = 1;
-          if (short[0] == "${namer.setterPrefix[0]}") type = 2;
+          var shortName = shortNames[j];
+          if (shortName[0] == "${namer.getterPrefix[0]}") type = 1;
+          if (shortName[0] == "${namer.setterPrefix[0]}") type = 2;
           // Generate call to:
           //
           //     createInvocationMirror(String name, internalName, type,
           //         arguments, argumentNames)
           //
-          objectClassObject[short] = (function(name, short,
-                                               type, #sliceOffsetParams) {
-              return function() {
-                return this.#noSuchMethodName(this,
-                    #createInvocationMirror(name, short, type,
-                        Array.prototype.slice.call(arguments,
-                                                   #sliceOffsetParams),
-                                                   []));
-              }
-          })(#names[j], short, type, #sliceOffsetArguments);
+
+          // This 'if' is either a static choice or dynamic choice depending on
+          // 'isIntercepted'.
+          if (#isIntercepted) {
+            objectClassObject[shortName] =
+                (function(name, shortName, type) {
+                  return function(receiver) {
+                    return this.#noSuchMethodName(
+                      receiver,
+                      #createInvocationMirror(name, shortName, type,
+                          Array.prototype.slice.call(arguments, 1),

[floitsch, 2015/06/19 21:22:15]

add comment what the "1" is.

[sra1, 2015/06/22 20:17:00]

Done.

+                          []));
+                  }
+                 })(#names[j], shortName, type);
+          } else {
+            objectClassObject[shortName] =
+                (function(name, shortName, type) {
+                  return function() {
+                    return this.#noSuchMethodName(
+                      this,  // Could be dummy receiver.

[floitsch, 2015/06/19 21:22:15]

how is that possible?
if the call is not intercepted then 'this' shouldn't be the dummy receiver. no?

Or are you saying that we could also pass a dummy-receiver? In that case change
the comment to: "// Value is ignored. We could also pass the dummy receiver.

[sra1, 2015/06/22 20:17:00]

Done.

+                      #createInvocationMirror(name, shortName, type,
+                          Array.prototype.slice.call(arguments),

[Siggi Cherem (dart-lang), 2015/06/19 18:33:22]

woudln't this return []? do we need splice here?

[sra1, 2015/06/19 18:59:38]

slice copies a slice of the input.
'arguments' contains all passed arguments, regardless of the function's declared
parameters.
We must copy since 'arguments' is not a JS Array, it is just 'array-like' which
is not good enough for Dart code.

In ES6 we would probably use  function(...args) {...}

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Obje...

[Siggi Cherem (dart-lang), 2015/06/19 19:46:00]

Then are we missing the 0 argument here? That is:

   Array.prototype.slice.call(arguments, 0)

instead of:
   Array.prototype.slice.call(arguments)

(the latter seems to return [])?

[sra1, 2015/06/22 20:17:00]

"If begin is omitted, slice begins from index 0."

$ function f(){return Array.prototype.slice.call(arguments)}
undefined
$ f(1,2,3)
[1, 2, 3]

[Siggi Cherem (dart-lang), 2015/06/22 20:37:32]

Sorry for all the silly questions here. Apparently I can't read. I originally
read splice instead of slice, and was playing with examples using `splice` and
hence the source of all my confusion.

It all makes sense now.

+                          []));
+                  }
+                 })(#names[j], shortName, type);
+          }
         }
       }''', {
-          'sliceOffsetParams': sliceOffsetParams,
           'noSuchMethodName': namer.noSuchMethodName,
           'createInvocationMirror': createInvocationMirror,
           'names': minify ? 'shortNames' : 'longNames',
-          'sliceOffsetArguments': sliceOffsetArguments}));
+          'isIntercepted': isIntercepted}));
 
     return statements;
   }
 }