Remove the trait selection impl in method::probe #43880
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arielb1
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LGTM (modulo how it fares in the wild, which is yet to be seen) r? @nikomatsakis |
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@bors try |
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⌛ Trying commit 7aecbc38c5c70f730eccb571290d02094cb9b6af with merge b96d5eea76e758bdd82fd4169eb4d5f7e3ce4fe2... |
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☀️ Test successful - status-travis |
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cc @rust-lang/infra Cargobomb requested. |
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☔ The latest upstream changes (presumably #43710) made this pull request unmergeable. Please resolve the merge conflicts. |
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I think I'm comfortable with landing this refactor the way it is, provided crater agrees. |
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Cargobomb run has started. |
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I read over the changes and r=me once we see the cargobomb results. |
arielb1
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Cargobomb results - http://cargobomb-reports.s3.amazonaws.com/pr-43880/index.html |
I think this has to depend on #43690 because that should fix the |
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LDAP report: |
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I think I fixed the LDAP problem with the new commit. |
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☔ The latest upstream changes (presumably #43690) made this pull request unmergeable. Please resolve the merge conflicts. |
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Now that the |
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☔ The latest upstream changes (presumably #43076) made this pull request unmergeable. Please resolve the merge conflicts. |
the data serves no purpose - it can be recovered from the obligation - and I think may leak stale inference variables into global caches.
This fixes a few cases of inference misses, some of them regressions caused by the impl selected for a method not being immediately evaluated.
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Ready for review, assuming higher-ranked function pointers will still impl |
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@bors r+
That part in particular doesn't seem to be controversial, I think...? |
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📌 Commit 15f6540 has been approved by |
It can't be, given that they are already |
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Aug 30, 2017
Remove the trait selection impl in method::probe This removes the hacky trait selection reimplementation in `method::probe`, which occasionally comes and causes problems. There are 2 issues I've found with this approach: 1. The older implementation sometimes had a "guess" type from an impl, which allowed subtyping to work. This is why I needed to make a change in `libtest`: there's an `impl<A> Clone for fn(A)` and we're calling `<for<'a> fn(&'a T) as Clone>::clone`. The older implementation would do a subtyping between the impl type and the trait type, so it would do the check for `<fn(A) as Clone>::clone`, and confirmation would continue with the subtyping. The newer implementation directly passes `<for<'a> fn(&'a T) as Clone>::clone` to selection, which fails. I'm not sure how big of a problem that would be in reality, especially after #43690 would remove the `Clone` problem, but I still want a crater run to avoid breaking the world. 2. The older implementation "looked into" impls to display error messages. I'm not sure that's an advantage - it looked exactly 1 level deep. r? @eddyb
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☀️ Test successful - status-appveyor, status-travis |
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This broke Servo. With have a fix (servo/servo#18327), but this does reject real code that was previously accepted. This should at least be noted in release notes. |
alexcrichton
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@SimonSapin Indeed -- I'm trying to figure out what is going on in that PR. Can you dump the struct definition on which the traceable derive was failing? |
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@SimonSapin I opened #44224 to discuss and decide on a resolution. Thanks for the regression report! |
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Changelog:
Version 1.21.0 (2017-10-12)
==========================
Language
--------
- [You can now use static references for literals.][43838]
Example:
```rust
fn main() {
let x: &'static u32 = &0;
}
```
- [Relaxed path syntax. Optional `::` before `<` is now allowed in all contexts.][43540]
Example:
```rust
my_macro!(Vec<i32>::new); // Always worked
my_macro!(Vec::<i32>::new); // Now works
```
Compiler
--------
- [Upgraded jemalloc to 4.5.0][43911]
- [Enabled unwinding panics on Redox][43917]
- [Now runs LLVM in parallel during translation phase.][43506]
This should reduce peak memory usage.
Libraries
---------
- [Generate builtin impls for `Clone` for all arrays and tuples that
are `T: Clone`][43690]
- [`Stdin`, `Stdout`, and `Stderr` now implement `AsRawFd`.][43459]
- [`Rc` and `Arc` now implement `From<&[T]> where T: Clone`, `From<str>`,
`From<String>`, `From<Box<T>> where T: ?Sized`, and `From<Vec<T>>`.][42565]
Stabilized APIs
---------------
[`std::mem::discriminant`]
Cargo
-----
- [You can now call `cargo install` with multiple package names][cargo/4216]
- [Cargo commands inside a virtual workspace will now implicitly
pass `--all`][cargo/4335]
- [Added a `[patch]` section to `Cargo.toml` to handle
prepublication dependencies][cargo/4123] [RFC 1969]
- [`include` & `exclude` fields in `Cargo.toml` now accept gitignore
like patterns][cargo/4270]
- [Added the `--all-targets` option][cargo/4400]
- [Using required dependencies as a feature is now deprecated and emits
a warning][cargo/4364]
Misc
----
- [Cargo docs are moving][43916]
to [doc.rust-lang.org/cargo](https://doc.rust-lang.org/cargo)
- [The rustdoc book is now available][43863]
at [doc.rust-lang.org/rustdoc](https://doc.rust-lang.org/rustdoc)
- [Added a preview of RLS has been made available through rustup][44204]
Install with `rustup component add rls-preview`
- [`std::os` documentation for Unix, Linux, and Windows now appears on doc.rust-lang.org][43348]
Previously only showed `std::os::unix`.
Compatibility Notes
-------------------
- [Changes in method matching against higher-ranked types][43880] This may cause
breakage in subtyping corner cases. [A more in-depth explanation is available.][info/43880]
- [rustc's JSON error output's byte position start at top of file.][42973]
Was previously relative to the rustc's internal `CodeMap` struct which
required the unstable library `libsyntax` to correctly use.
- [`unused_results` lint no longer ignores booleans][43728]
[42565]: rust-lang/rust#42565
[42973]: rust-lang/rust#42973
[43348]: rust-lang/rust#43348
[43459]: rust-lang/rust#43459
[43506]: rust-lang/rust#43506
[43540]: rust-lang/rust#43540
[43690]: rust-lang/rust#43690
[43728]: rust-lang/rust#43728
[43838]: rust-lang/rust#43838
[43863]: rust-lang/rust#43863
[43880]: rust-lang/rust#43880
[43911]: rust-lang/rust#43911
[43916]: rust-lang/rust#43916
[43917]: rust-lang/rust#43917
[44204]: rust-lang/rust#44204
[cargo/4123]: rust-lang/cargo#4123
[cargo/4216]: rust-lang/cargo#4216
[cargo/4270]: rust-lang/cargo#4270
[cargo/4335]: rust-lang/cargo#4335
[cargo/4364]: rust-lang/cargo#4364
[cargo/4400]: rust-lang/cargo#4400
[RFC 1969]: rust-lang/rfcs#1969
[info/43880]: rust-lang/rust#44224 (comment)
[`std::mem::discriminant`]: https://doc.rust-lang.org/std/mem/fn.discriminant.html
bors
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Nov 13, 2017
check::method - unify receivers before normalizing method signatures Normalizing method signatures can unify inference variables, which can cause receiver unification to fail. Unify the receivers first to avoid that. Fixes #36701. Fixes #45801. Fixes #45855. r? @eddyb beta-nominating because #43880 made this ICE happen in more cases (the code in that issue ICEs post-#43880 only, but the unit test here ICEs on all versions).
arielb1
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Nov 14, 2017
check::method - unify receivers before normalizing method signatures Normalizing method signatures can unify inference variables, which can cause receiver unification to fail. Unify the receivers first to avoid that. Fixes rust-lang#36701. Fixes rust-lang#45801. Fixes rust-lang#45855. r? @eddyb beta-nominating because rust-lang#43880 made this ICE happen in more cases (the code in that issue ICEs post-rust-lang#43880 only, but the unit test here ICEs on all versions).
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This removes the hacky trait selection reimplementation in
method::probe, which occasionally comes and causes problems.There are 2 issues I've found with this approach:
libtest: there's animpl<A> Clone for fn(A)and we're calling<for<'a> fn(&'a T) as Clone>::clone. The older implementation would do a subtyping between the impl type and the trait type, so it would do the check for<fn(A) as Clone>::clone, and confirmation would continue with the subtyping. The newer implementation directly passes<for<'a> fn(&'a T) as Clone>::cloneto selection, which fails. I'm not sure how big of a problem that would be in reality, especially after Generate builtin impls forClone#43690 would remove theCloneproblem, but I still want a crater run to avoid breaking the world.r? @eddyb