Replace mem::forget with ManuallyDrop::new
#3515
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
It's way less footgunny w.r.t. pointer aliasing:
- At worst, it's equivalent;
- But the advantage of `ManuallyDrop::new()`, is that it can be used
_before_ extracting data off the value, such as pointers, thereby
avoiding the danger of aliasing invalidation that `mem::forget` may
apply.
|
|
|
@danielhenrymantilla-codespace unfortunately you'll need to sign the CLA for us to be able to land this. Otherwise I can try and duplicate your PR: I haven't yet looked at the contents here. |
This comment was marked as outdated.
This comment was marked as outdated.
robertbastian
previously approved these changes
Jun 8, 2023
robertbastian
previously approved these changes
Jun 8, 2023
Manishearth
commented
Jun 8, 2023
| let capacity = vec.capacity(); | ||
| mem::forget(vec); | ||
| let len = vec.len(); | ||
| let ptr = mem::ManuallyDrop::new(vec).as_mut_ptr(); |
There was a problem hiding this comment.
ah, this is interesting, I was trying to figure out how best to fix the problem here
|
Thanks so much, this is great! |
robertbastian
approved these changes
Jun 8, 2023
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Part of #3510
Extracted from @danielhenrymantilla's PR #3514
It's way less footgunny w.r.t. pointer aliasing:
ManuallyDrop::new(), is that it can be usedbefore extracting data off the value, such as pointers, thereby
avoiding the danger of aliasing invalidation that
mem::forgetmayapply.