Reimplement ~const trait specialization
#133325
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
rustbot
added
S-waiting-on-review
compiler-errors
commented
Nov 22, 2024
| } | ||
|
|
||
| debug!("fulfill_implication: an impl for {:?} specializes {:?}", source_trait, target_trait); | ||
| // If the parent impl is const, then the specializing impl must be const. |
There was a problem hiding this comment.
Note to self: Actually I don't know if this is correct -- well, it's not sufficient.
const trait Bar {}
impl const Bar for T {}
const trait Foo {}
impl const Foo for T where T: ~const Bar {}
// specializing impl:
impl Foo for (T,) {}
The specializing impl satisfies (T,): ~const Bar because of the blanket impl, but it's still less const than the parent impl. I think we need to check that the specializing impl is also conditionally const, and then bail.
|
@rustbot author |
rustbot
added
S-waiting-on-author
compiler-errors
force-pushed
the
const-spec
branch
2 times, most recently
from
d1b64f1 to
ebfd56f
Compare
|
@rustbot ready |
rustbot
added
S-waiting-on-review
fee1-dead
requested changes
Nov 23, 2024
compiler-errors
force-pushed
the
const-spec
branch
from
5dc04d8 to
e41df70
Compare
lcnr
reviewed
Dec 2, 2024
| @@ -230,23 +231,26 @@ pub(super) fn specialization_enabled_in(tcx: TyCtxt<'_>, _: LocalCrate) -> bool | |||
| /// `impl1` specializes `impl2` if it applies to a subset of the types `impl2` applies | |||
There was a problem hiding this comment.
comment is outdated after your rename
There was a problem hiding this comment.
also, I feel like it's very helpful to explicitly write down "We therefore prove that the specializing impl implies the parent impl".
Because then it feels clear why we're instantiating the specializing impl with placeholders and the parent impl with existentials and prove all bounds of the parent impül
compiler-errors
force-pushed
the
const-spec
branch
from
e41df70 to
9bda88b
Compare
|
@bors r=lcnr,fee1-dead |
bors
added
S-waiting-on-bors
bors
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Dec 3, 2024
…iaskrgr Rollup of 6 pull requests Successful merges: - rust-lang#132723 (Unify `sysroot_target_{bin,lib}dir` handling) - rust-lang#133041 (Print name of env var in `--print=deployment-target`) - rust-lang#133325 (Reimplement `~const` trait specialization) - rust-lang#133395 (Add simd_relaxed_fma intrinsic) - rust-lang#133517 (Deeply normalize when computing implied outlives bounds) - rust-lang#133785 (Add const evaluation error UI test.) r? `@ghost` `@rustbot` modify labels: rollup
rust-timer
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Dec 3, 2024
Rollup merge of rust-lang#133325 - compiler-errors:const-spec, r=lcnr,fee1-dead Reimplement `~const` trait specialization Reimplement const specialization. We need this for `PartialEq` constification :) r? lcnr
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.
Reimplement const specialization. We need this for
PartialEqconstification :)r? lcnr