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digitalmars.D.bugs - [Issue 11382] New: Bad closure variable with scoped destruction

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=11382

           Summary: Bad closure variable with scoped destruction
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: accepts-invalid
          Severity: critical
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: k.hara.pg gmail.com


--- Comment #0 from Kenji Hara <k.hara.pg gmail.com> 2013-10-29 21:32:40 PDT ---
In the following code, compiler should reject the function 'foo' by
"has scoped destruction, cannot build closure" error.

struct S
{
    ~this() {}
}

auto foo()
{
    S s = S();
    return { s = S(); };
}

void main() {}

It is checked in toir.c FuncDeclaration::buildClosure(), however currently it
doesn't work for the variables which are explicitly declared on statement.

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=11382



--- Comment #1 from Kenji Hara <k.hara.pg gmail.com> 2013-10-29 21:33:06 PDT ---
Related discussion:
http://forum.dlang.org/thread/wsketyuhrbwiaetfbfww forum.dlang.org

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prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=11382


Maxim Fomin <maxim maxim-fomin.ru> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |maxim maxim-fomin.ru


--- Comment #2 from Maxim Fomin <maxim maxim-fomin.ru> 2013-10-30 05:48:08 PDT
---
I think this may break some code but I am not sure about that. 

What is more important is that conclusion in relevant threads was just not to
place dtor invocation in the end of function scope because stack struct touched
by closure is essentially object residing in the heap, and structs allocated in
the heap typically have no dtor call (unless they are wrapped into class or
some trick is used). Your proposal to reject code comes from nowhere and it is
unnecessary restrictive and does not fit into current practice: allocating
structs via new is allowed.

I think right solution is those raised into the thread: just disable dtor
invocation in the end of the function scope. Probably some temporal warning
will be needed.

In any case, except of struct touched by closure scenario, there are additional
cases which should be fixed: nested function and nested structs.

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prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=11382


Ali Cehreli <acehreli yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |acehreli yahoo.com


--- Comment #3 from Ali Cehreli <acehreli yahoo.com> 2013-10-30 14:16:37 PDT ---
The rest of the discussion:

  http://forum.dlang.org/post/l4osr0$2f3q$1 digitalmars.com

Ali

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