Replace A+Send trait subtyping with upcast coercion
#23423
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
|
r+ with nits fixed |
This upcast coercion currently preserves the vtable for the object, but eventually it can be used to create a derived vtable. The upcast coercion is not introduced into method dispatch; see comment on rust-lang#18737 for information about why. Fixes rust-lang#18737.
nikomatsakis
force-pushed
the
issue-18737-trait-subtyping
branch
from
d21339e
to
277b4f0
Compare
|
I addressed the nits but also changed the approach for |
|
@bors r=nrc 277b4f0 |
|
⌛ Testing commit 277b4f0 with merge c64d671... |
bors
added a commit
that referenced
this pull request
Mar 17, 2015
This upcast coercion currently never requires vtable changes. It should be generalized. This is a [breaking-change] -- if you have an impl on an object type like `impl SomeTrait`, then this will no longer be applicable to object types like `SomeTrait+Send`. In the standard library, this primarily affected `Any`, and this PR adds impls for `Any+Send` as to keep the API the same in practice. An alternate workaround is to use UFCS form or standalone fns. For more details, see <#18737 (comment)>. r? @nrc
Merged
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Outdated suggestions cannot be applied.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.
This upcast coercion currently never requires vtable changes. It should be generalized.
This is a [breaking-change] -- if you have an impl on an object type like
impl SomeTrait, then this will no longer be applicable to object types likeSomeTrait+Send. In the standard library, this primarily affectedAny, and this PR adds impls forAny+Sendas to keep the API the same in practice. An alternate workaround is to use UFCS form or standalone fns. For more details, see #18737 (comment).r? @nrc