RFR: 8314571: GrowableArray should move its old data and not copy it

[Quan Anh Mai]

On Fri, 18 Aug 2023 10:39:28 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

> Given some `GrowableArray<E>` where `E` is non-copyable with a move constructor will currently  fail to compile. This is because `GrowableArray`'s expand and shrink calls the copy constructor. We cast the values to rvalues (akin to `std::move`) to instead call the move constructor if available. If there is no move constructor but there is a copy constructor, then that will be called instead.

src/hotspot/share/utilities/growableArray.hpp line 545:

> 543:   if (len > 0) {
> 544:     new_data = static_cast<Derived*>(this)->allocate();
> 545:     for (int i = 0; i < len; ++i) ::new (&new_data[i]) E(static_cast<E&&>(old_data[i]));

Why not use `std::move`? Thanks.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/15344#discussion_r1299166458