Multiple binding expressions in radio button 'name' fields causes incorrect default values to be set

[zeiphon]

I'm submitting a ...

[X] bug report => search github for a similar issue or PR before submitting
[ ] feature request
[ ] support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question

Current behavior
Dynamically creating radio buttons with dynamic 'name' fields which contain more than one binding expression will not have the correct default values set.
e.g. within a nested ng-repeat:
<input type="radio" name="{{ expression1 }} {{ expression2 }}" ng-model="vm.radioModel[$index]" ... />
(Only the last radio button is selected.)
While using a combined expression will function correctly:
<input type="radio" name="{{ expression1 + expression2 }}" ng-model="vm.radioModel[$index]" ... />

Expected behavior
The default values for the radio options should be set according to the initially bound ng-model.

Minimal reproduction of the problem with instructions
Here's an example plunker demonstrating the issue: Incorrect default values set (plunker)

Here is an example plunker demonstrating the correct functioning of the same example, but using only one combined expression (e.g. name="{{ expression1 + expression2 }}):
Correct default values set (plunker)

Please tell us about your environment:
Windows 10 64bit

• Angular version: 1.5.x, 1.6.x

• Browser: Chrome 55

• Language: ES5

[gkalpak]

This happens because $watchGroup, which is used by $interpolate under the hood, has a different, async code path for strings with more than 1 interpolations (for performance reasons). This means that for a short period of time, all radios in your example will have the same (uninterpolated) name (i.e. {{one}}{{two}}), which will make the browser unselect all but the last selected one.

So, the easiest workaround is to use only one interpolation (as in your second example).

Usually, you don't need to set the name of radio buttons in Angular (it is taken care of automatically). Why do you need to set the names dynamically? (Just trying to understand the usecase better.)