[Issue 16084] Linker error with interface final function calling virtual function

May 27, 2016

Vladimir Panteleev

May 28, 2016

Jack Stouffer

May 28, 2016

Vladimir Panteleev

May 31, 2016

Jack Stouffer

https://issues.dlang.org/show_bug.cgi?id=16084 Vladimir Panteleev <thecybershadow@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |link-failure CC| |thecybershadow@gmail.com --- Comment #1 from Vladimir Panteleev <thecybershadow@gmail.com> --- How can this code be valid? You are declaring a templated function with no implementation. Templated functions cannot be virtual. I think this shouldn't even compile. --

https://issues.dlang.org/show_bug.cgi?id=16084 --- Comment #2 from Jack Stouffer <jack@jackstouffer.com> --- (In reply to Vladimir Panteleev from comment #1) > How can this code be valid? According to the spec ;) > You are declaring a templated function with no > implementation. Templated functions cannot be virtual. I think this > shouldn't even compile. If non final template functions aren't possible, then the compiler must check for this and the spec needs to be updated. I would like to know why this isn't possible though. --

May 28, 2016

[Issue 16084] Linker error with interface final function calling virtual function

Posted by Vladimir Panteleev

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Vladimir Panteleev

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https://issues.dlang.org/show_bug.cgi?id=16084

--- Comment #3 from Vladimir Panteleev <thecybershadow@gmail.com> ---
(In reply to Jack Stouffer from comment #2)
> (In reply to Vladimir Panteleev from comment #1)
> > How can this code be valid?
> 
> According to the spec ;)

It may be syntactically valid but it is semantically useless.

> > You are declaring a templated function with no
> > implementation. Templated functions cannot be virtual. I think this
> > shouldn't even compile.
> 
> If non final template functions aren't possible, then the compiler must check for this and the spec needs to be updated.

I think final is implied for template methods.

> I would like to know why this isn't possible though.

Because the compiler must generate a virtual function call table entry for every instantiation, but it can't do that unless it knows the instantiations ahead of time (i.e. which template arguments will that template be instantiated with ANYWHERE in the program). This is something that would only be possible if the D compiler had access to the source code of the entire program during compilation, which is not how it works currently (and would preclude partial compilation to machine code).

--

https://issues.dlang.org/show_bug.cgi?id=16084 Jack Stouffer <jack@jackstouffer.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |diagnostic --- Comment #4 from Jack Stouffer <jack@jackstouffer.com> --- Ok, I am changing this to an improved error message request. Also, IMO it should be mentioned on the interface page of the spec that template functions that don't use the interface template parameters are auto marked as final. --

https://issues.dlang.org/show_bug.cgi?id=16084 RazvanN <razvan.nitu1305@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |bootcamp CC| |razvan.nitu1305@gmail.com --

https://issues.dlang.org/show_bug.cgi?id=16084 Iain Buclaw <ibuclaw@gdcproject.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Priority|P1 |P3 --

https://issues.dlang.org/show_bug.cgi?id=16084 --- Comment #5 from dlangBugzillaToGithub <robert.schadek@posteo.de> --- THIS ISSUE HAS BEEN MOVED TO GITHUB https://github.com/dlang/dmd/issues/19134 DO NOT COMMENT HERE ANYMORE, NOBODY WILL SEE IT, THIS ISSUE HAS BEEN MOVED TO GITHUB --

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