[Issue 16058] `immutable delegate()` and `immutable delegate() immutable` are considered equal but treated differently

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16058

Iain Buclaw  changed:

   What|Removed |Added

   Priority|P1  |P3

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[Issue 16058] `immutable delegate()` and `immutable delegate() immutable` are considered equal but treated differently

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16058

timon.g...@gmx.ch changed:

   What|Removed |Added

 CC||timon.g...@gmx.ch

--- Comment #4 from timon.g...@gmx.ch ---
(In reply to Kenji Hara from comment #3)
> From the type qualifier transitivity, immutable(int* delegate()) should be
> same with immutable(int* delegate() immutable).
> ...

This does not follow from transitivity because the postfix `immutable` also
annotates the implicit context parameter of the function pointer while the
`immutable` qualifier on the delegate a priori does not.

If those two types are conflated this actually leads to type system
unsoundness:


auto foo()pure{
int x;
return ()pure{ return x++; };
}

void main(){
immutable dg=foo(); // can convert to immutable as it's a strongly pure
call
import std.stdio;
writeln(dg()," ",dg()); // 0 1, immutable context is modified
}


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[Issue 16058] `immutable delegate()` and `immutable delegate() immutable` are considered equal but treated differently

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16058

Bolpat  changed:

   What|Removed |Added

 CC||qs.il.paperi...@gmail.com

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[Issue 16058] `immutable delegate()` and `immutable delegate() immutable` are considered equal but treated differently

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16058

--- Comment #3 from Kenji Hara  ---
>From the type qualifier transitivity, immutable(int* delegate()) should be same
with immutable(int* delegate() immutable).

The root problem is in dmd implementation, TypeNext.makeXXX functions. Fixing
those implementation bugs is not difficult.

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[Issue 16058] `immutable delegate()` and `immutable delegate() immutable` are considered equal but treated differently

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16058

--- Comment #2 from ag0ae...@gmail.com ---
(In reply to Eyal Lotem from comment #1)
> I think it makes sense for the types not to be considered equal.
> (Head-mutable ptrs to immutable data exist, so why should delegates be
> inconsistent?)

A head mutable delegate would be `void delegate() immutable`, no? That is
considered different from the two types this is about.

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[Issue 16058] `immutable delegate()` and `immutable delegate() immutable` are considered equal but treated differently

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16058

Sobirari Muhomori  changed:

   What|Removed |Added

   See Also||https://issues.dlang.org/sh
   ||ow_bug.cgi?id=1983

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[Issue 16058] `immutable delegate()` and `immutable delegate() immutable` are considered equal but treated differently

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16058

Eyal Lotem  changed:

   What|Removed |Added

 CC||eyal.lo...@gmail.com

--- Comment #1 from Eyal Lotem  ---
I think it makes sense for the types not to be considered equal.
(Head-mutable ptrs to immutable data exist, so why should delegates be
inconsistent?)

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