Hi,

It seems that I found a bug in the compiler frontend, but I'm not completely sure that this is a bug, so first I'd like to ask people about that.

Given the description, the "with" statement is an equivalent of:

{
    Object tmp;
    tmp = expression;
    ...
    tmp.ident;
}

So, opDispatch() should probably be fine as well.
However, I found a case when it doesn't work as expected.

Let's take a code from the D Tour: https://tour.dlang.org/tour/en/gems/opdispatch-opapply

opDispatch() in this example is defined as a property, so there are two opDispatch() defined: one for "read" and another one for "write" cases.

But when I use this structure with the "with" statement (sorry for tautology), the compiler calls the wrong opDispatch().

Take a look at this example:

Shortened: https://run.dlang.io/is/pwbm0d
Gist: https://gist.github.com/run-dlang/a8fbbc5dc49346b887b9aaee8758ffca

Here is what I see in the AST info:

"""
with (test)
{
    (VariantN!32LU __tmpfordtor701 = ((VariantN!32LU __tmpfordtor700 = (*__withSym).opDispatch();) , __tmpfordtor700).opAssign(3.14);) , __tmpfordtor701;
}
writeln(test.opDispatch());
"""

Which means that instead of calling .opDispatch(val) to write a value, it calls opDispatch() to read a reference, and then opAssign() to set the value.

So the program throws a "Range Violation" exception.

I know that support for opDispatch() inside the "with" statement was added pretty recently: https://issues.dlang.org/show_bug.cgi?id=6400

However, it seems that the compiler generates different code for normal flow and for "with" statement, which is, probably, wrong.

Bug or not?
Should I create a bug report?

Thanks,
Jacob

On Monday, 14 January 2019 at 17:59:53 UTC, Jacob Shtokolov wrote:
>
> [..]

Nice catch!

> Bug or not?

Bug.

> Should I create a bug report?

Yes, please!

On Monday, 14 January 2019 at 20:43:35 UTC, Petar Kirov [ZombineDev] wrote:
> Nice catch!
>
>> Bug or not?
>
> Bug.

Thanks for your answer!

Reported: https://issues.dlang.org/show_bug.cgi?id=19588