[Issue 18087] New: "no property 'value' for type 'void'" when properties split among mixins

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18087

          Issue ID: 18087
           Summary: "no property 'value' for type 'void'" when properties
                    split among mixins
           Product: D
           Version: D2
          Hardware: x86
                OS: Mac OS X
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: jonathan at wilbur.space

I found what I believe is a bug in the way that Dlang deals with template
mixins containing properties.

The short story is: if you split the getter and setter between two mixin
templates, and if the got/set thing is a class (presumably it would work for a
struct too), and you try to retrieve a member of that class (or struct) you get
the error:

no property '???' for type 'void'

where '???' is the name of the member you attempted to access.

It's hard to explain, but here is my example below:


class Box { uint value = 5; }

mixin template tempy1()
{
    public @property void points (Box p)
    {
        this._points = p;
    }
// }

// mixin template tempy2()
// {
    public @property Box points ()
    {
        return this._points;
    }
}

class Foo
{
    private Box _points;
    mixin tempy1;
    // mixin tempy2;
    unittest { assert((new Foo()).points.value == 5); }
}


Pardon the compression. With all of the comments in place, this compiles just
fine, but remove all of the comments, and you'll see the error message
described above. Note, again, that this problem only occurs when the get/set
thing is a class (again, maybe a struct too).

Maybe there is a little quirk about properties that I have missed, but I
reviewed the documentation on properties, and it does not seem like this should
happen. Strangely, it seems like removing the setter makes the above compile,
even without the comments.

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