Issue with dmd 2.066, alias this, and sort

[bearophile via Digitalmars-d-learn]

rcor:

> I've tried to express my problem in a mostly minimal example 
> here:
> https://gist.github.com/murphyslaw480/d4a5f857a104bcf62de1
>
> The class Point has an alias this to its own property 
> 'feature()', which returns a reference to a private member. 
> When I try to sort a Point[], DMD fails with "mutable method 
> feature is not callable on const object". I'm not actually 
> using the property 'feature()' or the alias this in the 
> sorting, so it seems like it shouldn't interfere. That being 
> said, I'm still slightly const-challenged so maybe its an error 
> on my part. However, the above example compiles fine with DMD 
> 2.065.0-3.

It compiles if you use:
@property auto feature() const pure nothrow { return _feature; }

Otherwise I get strange errors like:

...\dmd2\src\phobos\std\exception.d(986,31): Error: pure function 
'std.exception.doesPointTo!(Point, Point, void).doesPointTo' 
cannot call impure function 'temp.Point.feature'

Bye,
bearophile