In TrackByFn typedef, index parameter should be an int not a num

[chalin]

Under Dart 1.24-dev, when compiling https://github.com/angular-examples/template-syntax using the dartdevc I get this errors:

[error] A value of type '(int, Hero) → int' can't be assigned to a variable of type 'TrackByFn(num, dynamic) → dynamic'. (package:template_syntax/app_component.template.dart, line 4013, col 35)

This is because the app declares the following function used as an argument to an ngFor trackBy:

int trackByHeroes(int index, Hero hero) => hero.id;

But Angular seems to expect the index to be a num; see lib/src/core/change_detection/differs/default_iterable_differ.dart#L10

typedef dynamic TrackByFn(num index, dynamic item);

Should index not just be an int? It seems to only ever be called with an index that is an int.

cc @kwalrath

[matanlurey]

Yep I'll update it for 4.0!

…

On Tue, Jun 6, 2017, 5:53 PM Patrice Chalin ***@***.***> wrote: Under Dart 1.24-dev, when compiling https://github.com/angular-examples/template-syntax using the dartdevc I get this errors: [error] A value of type '(int, Hero) → int' can't be assigned to a variable of type 'TrackByFn(num, dynamic) → dynamic'. (package:template_syntax/app_component.template.dart, line 4013, col 35) This is because the app declares the following function used as an argument to an ngFor trackBy: int trackByHeroes(int index, Hero hero) => hero.id; But Angular seems to expect the index to be a num; see lib/src/core/change_detection/differs/default_iterable_differ.dart#L10 <https://github.com/dart-lang/angular2/blob/master/lib/src/core/change_detection/differs/default_iterable_differ.dart#L10> typedef dynamic TrackByFn(num index, dynamic item); Should index not just be an int? It seems to only ever be called <https://github.com/dart-lang/angular2/blob/master/lib/src/core/change_detection/differs/default_iterable_differ.dart#L210> with an index that is an int <https://github.com/dart-lang/angular2/blob/master/lib/src/core/change_detection/differs/default_iterable_differ.dart#L202> . cc @kwalrath <https://github.com/kwalrath> — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#431>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAKQ7pBfbvsyBBugVIOjPTWqLbQkbgRmks5sBfSBgaJpZM4NyFBP> .

[matanlurey]

Will be fixed in the next sync, but that will be a little while :-/

[kevin-sakemaer]

i got the same problem yesterday and if you change the Hero to dynamic and the returned type to dynamic it work. but that is not really good

[matanlurey]

Landed.