Bug in dmd?

[Andrey Zherikov]

On Wednesday, 15 June 2022 at 09:21:28 UTC, user1234 wrote:
> On Tuesday, 14 June 2022 at 13:39:12 UTC, Andrey Zherikov wrote:
>> I have [pretty simple code in my 
>> library](https://github.com/andrey-
>> [Line (2) 
>> produces](https://github.com/andrey-zherikov/argparse/runs/6880350900?check_suite_focus=true#step:5:12) `undefined reference to '_D3std7sumtype__T7SumTypeTS8argparse4help2AATSQtQm2BBZQBl6__dtorMFNaNbNiNfZv'` (it demangles to `pure nothrow @nogc @safe void std.sumtype.SumType!(argparse.help.AA, argparse.help.BB).SumType.__dtor()`)
>>
>> If I comment line (2) then everything is good (no link 
>> errors). Note that there is the same code at (1) which doesn't 
>> produce any error. Any idea what's going on?
>
> That can be a template instance that's emitted somewhere else, 
> i.e the thing is there but the mangle is different. maybe try 
> to find if the dtor is there with `mn -S` on each object.
>
> Another thing to try in these situations is to see if that 
> works with `-allinst`.

I tried to call dmd the same way as dub does with `-allinst` 
added to all calls. Got the same linker issue.

`nm` shows that `app.d` refers to dtor which is not defined in 
`.a`:
```bash
$ nm .../liball_argparse.a|egrep 'argparse.+dtor'
$ nm .../all_getting_started-basic.o|egrep 'argparse.+dtor'
                  U 
_D3std7sumtype__T7SumTypeTS8argparse4help2AATSQtQm2BBZQBl6__dtorMFNaNbNiNfZv
```