Rollup of 3 pull requests #23861
Merged
Rollup of 3 pull requests #23861
Conversation
This file contains hidden or 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
…tring, r=alexcrichton closes rust-lang#23620 This PR patches the issue mentioned in rust-lang#23620, but there is also an ICE for invalid escape sequences in byte literals. This is due to the fact that the `scan_byte` function returns ` token::intern(\"??\") ` for invalid bytes, resulting in an ICE later on. Is there a reason for this behavior? Shouldn't `scan_byte` fail when it encounters an invalid byte? And I noticed a small inconsistency in the documentation. According to the formal byte literal definition in http://doc.rust-lang.org/reference.html#byte-and-byte-string-literals , a byte string literal contains `string_body *`, but according to the text (and the behavior of the lexer) it should not accept unicode escape sequences. Hence it should be replaced by `byte_body *`. If this is valid, I can add this fix to this PR.
This PR introduces a `Reflect` marker trait which is a supertrait of `Any`. The idea is that `Reflect` is defined for all concrete types, but is not defined for type parameters unless there is a `T:Reflect` bound. This is intended to preserve the parametricity property. This allows the `Any` interface to be stabilized without committing us to unbounded reflection that is not easily detectable by the caller. The implementation of `Reflect` relies on an experimental variant of OIBIT. This variant behaves differently for objects, since it requires that all types exposed as part of the object's *interface* are `Reflect`, but isn't concerned about other types that may be closed over. In other words, you don't have to write `Foo+Reflect` in order for `Foo: Reflect` to hold (where `Foo` is a trait). Given that `Any` is slated to stabilization and hence that we are committed to some form of reflection, the goal of this PR is to leave our options open with respect to parametricity. I see the options for full stabilization as follows (I think an RFC would be an appropriate way to confirm whichever of these three routes we take): 1. We make `Reflect` a lang-item. 2. We stabilize some version of the OIBIT variation I implemented as a general mechanism that may be appropriate for other use cases. 3. We give up on preserving parametricity here and just have `impl<T> Reflect for T` instead. In that case, `Reflect` is a harmless but not especially useful trait going forward. cc @aturon cc @alexcrichton cc @glaebhoerl (this is more-or-less your proposal, as I understood it) cc @reem (this is more-or-less what we discussed on IRC at some point) cc @flaper87 (vaguely pertains to OIBIT)
…ing-syntax, r=aturon This syntax has been deprecated for quite some time, and there were only a few remaining uses of it in the codebase anyway.
Contributor
|
r? @huonw (rust_highfive has picked a reviewer for you, use r? to override) |
Member
Author
|
@bors: r+ p=2 |
Collaborator
|
📌 Commit 414d3e7 has been approved by |
Member
Author
|
@bors: r+ p=2 |
Collaborator
|
📌 Commit 3b45470 has been approved by |
Collaborator
|
⌛ Testing commit 3b45470 with merge 6cf3b0b... |
Collaborator
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
6 participants
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.
std::errorexample #23836, lint: handle private traits better #23852