diff options
| author | Manish Goregaokar <manishsmail@gmail.com> | 2016-03-26 20:35:49 +0530 |
|---|---|---|
| committer | Manish Goregaokar <manishsmail@gmail.com> | 2016-03-26 20:35:49 +0530 |
| commit | 4a1e19990fefbf69aca5ddc9fbc0a2d20e7f6b0d (patch) | |
| tree | 2f3072ec65c71a91723d2cd605bbda1691abb172 /src/doc | |
| parent | c9b6ba800aba1e4caf8548904d2957f5cfda2758 (diff) | |
| parent | bb43f580e5a291ee02a99b6dca6ec9b757151a19 (diff) | |
| download | rust-4a1e19990fefbf69aca5ddc9fbc0a2d20e7f6b0d.tar.gz rust-4a1e19990fefbf69aca5ddc9fbc0a2d20e7f6b0d.zip | |
Rollup merge of #32383 - aidanhs:aphs-heap-move-guarantee, r=alexcrichton
Document heap allocation location guarantee ``` 14:25 < aidanhs> is there any guarantee that boxes will not move the value on the heap when they are moved? 14:26 <@steveklabnik> aidanhs: ... i'm not sure if it's a guarantee, but it follows, generally 14:26 <@steveklabnik> aidanhs: moves mean memcpy, so you're memcpying the structure of the box itself, which is copying the pointer 14:26 <@steveklabnik> so the pointer won't be updated 14:26 <@steveklabnik> moves cannot do complex things like move the memory around on the heap 14:26 <@kmc> aidanhs: I would say it's guaranteed 14:27 < aidanhs> steveklabnik: yeah, that's what I was thinking, it'd be pretty strange for rust to do something, but I couldn't find any docs one way or the other 14:27 <@steveklabnik> kmc: aidanhs yeah, it's like a borderline thing that we don't explicitly guanratee but i think IS guaranteed by our other guarantees 14:27 <@steveklabnik> mostly that move == memcpy 14:28 < aidanhs> kmc: steveklabnik great thanks! would a PR to the rust reference along these lines be ok? 14:28 < jmesmon> aidanhs: I believe owning_ref has some discussion of that (stable references) 14:29 <@steveklabnik> aidanhs: i would probably take that, yeah 14:29 < aidanhs> jmesmon: thanks, I'll take a look at that ``` https://botbot.me/mozilla/rust/2016-02-22/?msg=60657619&page=18 r? @steveklabnik
Diffstat (limited to 'src/doc')
| -rw-r--r-- | src/doc/reference.md | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/src/doc/reference.md b/src/doc/reference.md index 3325749d94c..fcf9aefaba8 100644 --- a/src/doc/reference.md +++ b/src/doc/reference.md @@ -3911,6 +3911,9 @@ The _heap_ is a general term that describes boxes. The lifetime of an allocation in the heap depends on the lifetime of the box values pointing to it. Since box values may themselves be passed in and out of frames, or stored in the heap, heap allocations may outlive the frame they are allocated within. +An allocation in the heap is guaranteed to reside at a single location in the +heap for the whole lifetime of the allocation - it will never be relocated as +a result of moving a box value. ### Memory ownership |