On Tuesday, 9 February 2016 at 13:45:13 UTC, Hara Kenji wrote:
On Tuesday, 9 February 2016 at 00:25:33 UTC, Matt Elkins wrote:
On Thursday, 4 February 2016 at 02:33:06 UTC, Andrei
Alexandrescu wrote:
Got it, thanks. That's a bug in the implementation, no two
ways about it. No copy should occur there, neither
theoretically nor practically. Please report it to bugzilla
at http://issues.dlang.org. Thanks very much! -- Andrei
Done (sorry for the delay):
https://issues.dlang.org/show_bug.cgi?id=15662
I've replied to issue 15662.
The point of that issue is, an array concatenation or appending
may cause the elements' copy.
The copy occurrence is determined by the runtime situation, so
compiler needs to reject such the operation for the @disable
this(this) elements conservatively.
Kenji Hara
Actually, I have a follow-up question about this: when you say
that an array concatenation may cause the elements' copy, do you
mean only the element being appended? Or can elements already in
the array be copied? If the latter, isn't it a problem that my
workaround for appending non-copyable objects into the array
compiles?
My workaround is like this (typing directly without testing):
// Foo has opAssign defined for rvalues, but post-blit and
opAssign for lvalues disabled
Foo[] fooArray;
++fooArray.length;
fooArray[$ - 1] = Foo();
