[Issue 13833] .classinfo.name (and typeid(obj)) does not print proper dynamic type when using a templated interface

[Issue 13833] .classinfo.name (and typeid(obj)) does not print proper dynamic type when using an interface

Jul 21, 2015

Kenji Hara

Sep 04, 2016

Lodovico Giaretta

Jan 26, 2021

Adam D. Ruppe

Dec 17, 2022

Iain Buclaw

Dec 13

dlangBugzillaToGithub

https://issues.dlang.org/show_bug.cgi?id=13833 Andrei Alexandrescu <andrei@erdani.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Version|D1 & D2 |D2 --

July 21, 2015

[Issue 13833] .classinfo.name (and typeid(obj)) does not print proper dynamic type when using an interface

Posted by Kenji Hara

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Kenji Hara

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https://issues.dlang.org/show_bug.cgi?id=13833

Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|.classinfo.name (and        |.classinfo.name (and
                   |typeid(obj)) does not print |typeid(obj)) does not print
                   |proper dynamic type when    |proper dynamic type when
                   |using a templated interface |using an interface

--- Comment #2 from Kenji Hara <k.hara.pg@gmail.com> ---
The issue also happens with non-template interface.

interface I { }
class D : I { }

void main()
{
    I i = new D;
    writeln(typeid(i));
    writeln(i.classinfo.name);  // ditto
}

Currently typeid() on interface reference returns the TypeInfo of "most derived" implemented interface.

import std.stdio;

interface I {}
interface J : I {}
interface K : I {}
class E : J, K {}

void main()
{
    E e = new E;
    J j = e;
    K k = e;
    I ij = j;
    I ik = k;
    writeln(typeid(ij));      // prints 'test.J'
    writeln(typeid(ik));      // prints 'test.K'
}

The interface references ij an ik point different positions of class instance e, so the two typeid()s also return different TypeInfo objects.

--

https://issues.dlang.org/show_bug.cgi?id=13833 Lodovico Giaretta <lodovico@giaretart.net> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |lodovico@giaretart.net --- Comment #3 from Lodovico Giaretta <lodovico@giaretart.net> --- Being pedantic, the spec does not state what happens when the static type of the expression is an interface. In fact it says that "if the type is a class, it returns the TypeInfo of the dynamic type (i.e. the most derived type)". But the current behaviour is certainly a bug, and very confusing when encountered. See for example http://forum.dlang.org/thread/gdjaoxypicsxlfvzwbvt@forum.dlang.org This is worth a bugfix in both the implementation and the documentation. --

https://issues.dlang.org/show_bug.cgi?id=13833 Adam D. Ruppe <destructionator@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |destructionator@gmail.com --- Comment #4 from Adam D. Ruppe <destructionator@gmail.com> --- the compiler could prolly just auto-cast to object then typeid it --

https://issues.dlang.org/show_bug.cgi?id=13833 Iain Buclaw <ibuclaw@gdcproject.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Priority|P1 |P3 --

https://issues.dlang.org/show_bug.cgi?id=13833 --- Comment #5 from dlangBugzillaToGithub <robert.schadek@posteo.de> --- THIS ISSUE HAS BEEN MOVED TO GITHUB https://github.com/dlang/dmd/issues/18921 DO NOT COMMENT HERE ANYMORE, NOBODY WILL SEE IT, THIS ISSUE HAS BEEN MOVED TO GITHUB --

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