const_evaluatable_checked: fix occurs check
fixes#79615
this is kind of a hack because we use `TypeRelation` for both the `Generalizer` and the `ConstInferUnifier` but i am not sure if there is a useful way to disentangle this without unnecessarily duplicating some code.
The error in the added test is kind of unavoidable until we erase the unused substs of `ConstKind::Unevaluated`. We talked a bit about this in the cg lazy norm meeting (https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/lazy_normalization_consts)
Improve and fix diagnostics of exhaustiveness checking
Primarily, this fixes https://github.com/rust-lang/rust/issues/56379. This also fixes incorrect interactions between or-patterns and slice patterns that I discovered while working on #56379. Those two examples show the incorrect diagnostics:
```rust
match &[][..] {
[true] => {}
[true // detected as unreachable but that's not true
| false, ..] => {}
_ => {}
}
match (true, None) {
(true, Some(_)) => {}
(false, Some(true)) => {}
(true | false, None | Some(true // should be detected as unreachable
| false)) => {}
}
```
I did not measure any perf impact. However, I suspect that [`616ba9f`](https://github.com/rust-lang/rust/pull/80104/commits/616ba9f9f7f5845777a36e1a41a515e6c33a8776) should have a negative impact on large or-patterns. I'll see what the perf run says; I have optimization ideas up my sleeve if needed.
EDIT: I initially had a noticeable perf impact that I thought unavoidable. I then proceeded to avoid it x)
r? `@varkor`
`@rustbot` label +A-exhaustiveness-checking
passes: prohibit invalid attrs on generic params
Fixes#78957.
This PR modifies the `check_attr` pass so that attribute placement on generic parameters is checked for validity.
r? `@lcnr`
Rollup of 5 pull requests
Successful merges:
- #78164 (Prefer regions with an `external_name` in `approx_universal_upper_bound`)
- #80003 (Fix overflow when converting ZST Vec to VecDeque)
- #80023 (Enhance error message when misspelled label to value in break expression)
- #80046 (Add more documentation to `Diagnostic` and `DiagnosticBuilder`)
- #80109 (Remove redundant and unreliable coverage test results)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Prefer regions with an `external_name` in `approx_universal_upper_bound`
Fixes#75785
When displaying a MIR borrowcheck error, we may need to find an upper
bound for a region, which gives us a region to point to in the error
message. However, a region might outlive multiple distinct universal
regions, in which case the only upper bound is 'static
To try to display a meaningful error message, we compute an
'approximate' upper bound by picking one of the universal regions.
Currently, we pick the region with the lowest index - however, this
caused us to produce a suboptimal error message in issue #75785
This PR `approx_universal_upper_bound` to prefer regions with an
`external_name`. This causes us to prefer regions from function
arguments/upvars, which seems to lead to a nicer error message in some
cases.
Fixes#75785
When displaying a MIR borrowcheck error, we may need to find an upper
bound for a region, which gives us a region to point to in the error
message. However, a region might outlive multiple distinct universal
regions, in which case the only upper bound is 'static
To try to display a meaningful error message, we compute an
'approximate' upper bound by picking one of the universal regions.
Currently, we pick the region with the lowest index - however, this
caused us to produce a suboptimal error message in issue #75785
This PR `approx_universal_upper_bound` to prefer regions with an
`external_name`. This causes us to prefer regions from function
arguments/upvars, which seems to lead to a nicer error message in some
cases.
Move binder for dyn to each list item
This essentially changes `ty::Binder<&'tcx List<ExistentialTraitRef>>` to `&'tcx List<ty::Binder<ExistentialTraitRef>>`.
This is a first step in moving the `dyn Trait` representation closer to Chalk, which we've talked about in `@rust-lang/wg-traits.`
r? `@nikomatsakis`
Fix issue #78496
EarlyOtherwiseBranch finds MIR structures like:
```
bb0: {
...
_2 = discriminant(X)
...
switchInt(_2) -> [1_isize: bb1, otherwise: bb3]
}
bb1: {
...
_3 = discriminant(Y)
...
switchInt(_3) -> [1_isize: bb2, otherwise: bb3]
}
bb2: {...}
bb3: {...}
```
And transforms them into something like:
```
bb0: {
...
_2 = discriminant(X)
_3 = discriminant(Y)
_4 = Eq(_2, _3)
switchInt(_4) -> [true: bb4, otherwise: bb3]
}
bb2: {...} // unchanged
bb3: {...} // unchanged
bb4: {
switchInt(_2) -> [1_isize: bb2, otherwise: bb3]
}
```
But that is not always a safe thing to do -- sometimes the early `otherwise` branch is necessary so the later block could assume the value of `discriminant(X)`.
I am not totally sure what's the best way to detect that, but fixing #78496 should be easy -- we just check if `X` is a sub-expression of `Y`. A more precise test might be to check if `Y` contains a `Downcast(1)` of `X`, but I think this might be good enough.
Fix#78496
Allow `since="TBD"` for rustc_deprecated
Closes#78381.
This PR only affects `#[rustc_deprecated]`, not `#[deprecated]`, so there is no effect on any stable language feature.
Likewise this PR only implements `since="TBD"`, it does not actually tag any library functions with it, so there is no effect on any stable API.
Overview of changes:
* `rustc_middle/stability.rs`:
* change `deprecation_in_effect` function to return `false` when `since="TBD"`
* tidy up the compiler output when a deprecated item has `since="TBD"`
* `rustc_passes/stability.rs`:
* allow `since="TBD"` to pass the sanity check for stable_version < deprecated_version
* refactor the "invalid stability version" and "invalid deprecation version" error into separate errors
* rustdoc: make `since="TBD"` message on a deprecated item's page match the command-line deprecation output
* tests:
* test rustdoc output
* test that the `deprecated_in_future` lint fires when `since="TBD"`
* test the new "invalid deprecation version" error message
Implement if-let match guards
Implements rust-lang/rfcs#2294 (tracking issue: #51114).
I probably should do a few more things before this can be merged:
- [x] Add tests (added basic tests, more advanced tests could be done in the future?)
- [x] Add lint for exhaustive if-let guard (comparable to normal if-let statements)
- [x] Fix clippy
However since this is a nightly feature maybe it's fine to land this and do those steps in follow-up PRs.
Thanks a lot `@matthewjasper` ❤️ for helping me with lowering to MIR! Would you be interested in reviewing this?
r? `@ghost` for now
Take into account negative impls in "trait item not found" suggestions
This removes the suggestion to implement a trait for a type when that type already has a negative implementation for the trait, and replaces it with a note to point out that the trait is explicitely unimplemented, as suggested by `@scottmcm.`
Helps with #79683.
r? `@scottmcm` do you want to review this?
consider assignments of union field of ManuallyDrop type safe
Assigning to `Copy` union fields is safe because that assignment will never drop anything. However, with https://github.com/rust-lang/rust/pull/77547, unions may also have `ManuallyDrop` fields, and their assignments are currently still unsafe. That seems unnecessary though, as assigning `ManuallyDrop` does not drop anything either, and is thus safe even for union fields.
I assume this will at least require FCP.
Properly capture trailing 'unglued' token
If we try to capture the `Vec<u8>` in `Option<Vec<u8>>`, we'll
need to capture a `>` token which was 'unglued' from a `>>` token.
The processing of unglueing a token for parsing purposes bypasses the
usual capturing infrastructure, so we currently lose the trailing `>`.
As a result, we fall back to the reparsed `TokenStream`, causing us to
lose spans.
This commit makes token capturing keep track of a trailing 'unglued'
token. Note that we don't need to care about unglueing except at the end
of the captured tokens - if we capture both the first and second unglued
tokens, then we'll end up capturing the full 'glued' token, which
already works correctly.
Recover on `const impl<> X for Y`
`@leonardo-m` mentioned that `const impl Foo for Bar` could be recovered from in #79287.
I'm not sure about the error strings as they are, I think it should probably be something like the error that `expected_one_of_not_found` makes + the suggestion to flip the keywords, but I'm not sure how exactly to do that. Also, I decided not to try to handle `const unsafe impl` or `unsafe const impl` cause I figured that `unsafe impl const` would be pretty rare anyway (if it's even valid?), and it wouldn't be worth making the code more messy.
Resolve enum field visibility correctly
Fixes#79593. 🎉
Previously, this code treated enum fields' visibility as if they were
struct fields. However, that's not correct because the visibility of a
struct field with `ast::VisibilityKind::Inherited` is private to the
module it's defined in, whereas the visibility of an *enum* field with
`ast::VisibilityKind::Inherited` is the visibility of the enum it
belongs to.
Previously, this code treated enum fields' visibility as if they were
struct fields. However, that's not correct because the visibility of a
struct field with `ast::VisibilityKind::Inherited` is private to the
module it's defined in, whereas the visibility of an *enum* field with
`ast::VisibilityKind::Inherited` is the visibility of the enum it
belongs to.
If we try to capture the `Vec<u8>` in `Option<Vec<u8>>`, we'll
need to capture a `>` token which was 'unglued' from a `>>` token.
The processing of unglueing a token for parsing purposes bypasses the
usual capturing infrastructure, so we currently lose the trailing `>`.
As a result, we fall back to the reparsed `TokenStream`, causing us to
lose spans.
This commit makes token capturing keep track of a trailing 'unglued'
token. Note that we don't need to care about unglueing except at the end
of the captured tokens - if we capture both the first and second unglued
tokens, then we'll end up capturing the full 'glued' token, which
already works correctly.
Capture precise paths in THIR and MIR
This PR allows THIR and MIR to use the result of the new capture analysis to actually capture precise paths
To achieve we:
- Writeback min capture results to TypeckResults
- Move handling upvars to PlaceBuilder in mir_build
- Lower precise paths in THIR build by reading min_captures
- Search for ancestors in min_capture when trying to build a MIR place which starts off of an upvar
Closes: https://github.com/rust-lang/project-rfc-2229/issues/10
Partly implements: rust-lang/project-rfc-2229#18
Work that remains (not in this PR):
- [ ] [Known bugs when feature gate is enabled](https://github.com/rust-lang/project-rfc-2229/projects/1?card_filter_query=label%3Abug)
- [ ] Use min_capure_map for
- [ ] Liveness analysis
- [ ] rustc_mir/interpret/validity.rs
- [ ] regionck
- [ ] rust-lang/project-rfc-2229#8
- [ ] remove closure_captures and upvar_capture_map
r? `@ghost`
CTFE: tweak abort-on-uninhabited message
Having an "aborted execution:" makes it more consistent with the `Abort` terminator saying "the program aborted execution". Right now, at least one of the two errors will look weird in Miri.
r? `@oli-obk`
Clarify the 'default is only allowed on...' error
Code like
impl Foo {
default fn foo() {}
}
will trigger the error
error: `default` is only allowed on items in `impl` definitions
--> src/lib.rs:5:5
|
5 | default fn foo() {}
| -------^^^^^^^^^
| |
| `default` because of this
but that's very confusing! I *did* put it on an item in an impl!
So this commit changes the message to
error: `default` is only allowed on items in trait impls
--> src/lib.rs:5:5
|
5 | default fn foo() {}
| -------^^^^^^^^^
| |
| `default` because of this
Constier maybe uninit
I was playing around trying to make `[T; N]::zip()` in #79451 be `const fn`. One of the things I bumped into was `MaybeUninit::assume_init`. Is there any reason for the intrinsic `assert_inhabited<T>()` and therefore `MaybeUninit::assume_init` not being `const`?
---
I have as best as I could tried to follow the instruction in [library/core/src/intrinsics.rs](https://github.com/rust-lang/rust/blob/master/library/core/src/intrinsics.rs#L11). I have no idea what I am doing but it seems to compile after some slight changes after the copy paste. Is this anywhere near how this should be done?
Also any ideas for name of the feature gate? I guess `const_maybe_assume_init` is quite misleading since I have added some more methods. Should I add test? If so what should be tested?
