[Issue 16197] Constructors/postblits and destructors don't match up for array initialisation (page 2)

https://issues.dlang.org/show_bug.cgi?id=16197 --- Comment #8 from Sobirari Muhomori <dfj1esp02@sneakemail.com> --- (In reply to David Nadlinger from comment #5) > I'm not sure how to reconcile the number of ctor/postblit calls with the number of dtor calls, though. ctor+postblit=dtor indeed, the original test case correctly tracks dtors by printing value assigned to the x field. --

May 12, 2017

[Issue 16197] Constructors/postblits and destructors don't match up for array initialisation

Posted by Walter Bright

Permalink

Walter Bright

Permalink

https://issues.dlang.org/show_bug.cgi?id=16197

Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla@digitalmars.com
           Severity|critical                    |enhancement

--- Comment #9 from Walter Bright <bugzilla@digitalmars.com> ---
(In reply to Max Samukha from comment #7)
> Should be either two destructors or no postblit. For "Elem arr" instead of "Elem[1] arr", only the destructor is correctly called once.

What's happening here is that arrays are constructed by calling _d_arraysetctor(). That works by passing it an instance of the object Elem being constructed, which is the Elem.init object, and then copying it into arr[1]. The copy operation invokes the postblit.

The code doing the postblit is here:

https://github.com/dlang/druntime/blob/master/src/rt/arrayassign.d#L245

Then when it goes out of scope, the destructor is called.

That's why you see a single postblit and a single destructor.

The code is not incorrect, this is not a bug. However, it can be improved to skip the postblit for default initialization.

Therefore, I'm going to re-categorize this as an enhancement request.

--

https://issues.dlang.org/show_bug.cgi?id=16197 David Nadlinger <code@klickverbot.at> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|enhancement |critical --- Comment #10 from David Nadlinger <code@klickverbot.at> --- Could you please comment on the other test cases as well? I'm not convinced that they are equivalent (i.e. equivalently valid behaviour). --

https://issues.dlang.org/show_bug.cgi?id=16197 --- Comment #11 from Walter Bright <bugzilla@digitalmars.com> --- Another effect you are seeing is default construction, which should account for more destructors and postblits than constructor calls. --

https://issues.dlang.org/show_bug.cgi?id=16197 Walter Bright <bugzilla@digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|critical |enhancement --- Comment #12 from Walter Bright <bugzilla@digitalmars.com> --- https://github.com/dlang/dmd/pull/6774 David, if you feel there are further issues here, please file a separate issue with a minimal example. --

https://issues.dlang.org/show_bug.cgi?id=16197 --- Comment #13 from Eyal <eyal@weka.io> --- The dmd output was correct (ignoring irrelevant POSTBLIT -1) - w.r.t number of ctors/postblits & dtors. The ldc output is now correct in version: LDC - the LLVM D compiler (1.1.0git-3139c87): based on DMD v2.071.2 and LLVM 3.8.0 built with LDC - the LLVM D compiler (31eb0f) So the bug can be closed as fixed afaic. --

https://issues.dlang.org/show_bug.cgi?id=16197 --- Comment #14 from Walter Bright <bugzilla@digitalmars.com> --- (In reply to Eyal from comment #13) > So the bug can be closed as fixed afaic. Thanks! But I still think you'll like the PR I made for this, as it improves performance. --

https://issues.dlang.org/show_bug.cgi?id=16197 --- Comment #15 from github-bugzilla@puremagic.com --- Commits pushed to master at https://github.com/dlang/dmd https://github.com/dlang/dmd/commit/10c4f4acb524940cf5747bf6406dd51a13e7fbd2 fix Issue 16197 - Constructors/postblits and destructors don't match up for array initialisation https://github.com/dlang/dmd/commit/ca5a785e5ebe56a1019189801002ea214362a1f6 Merge pull request #6774 from WalterBright/fix16197 fix Issue 16197 - Constructors/postblits and destructors don't match … merged-on-behalf-of: Daniel Murphy <yebblies@gmail.com> --

Forums