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1590 Commits

Author SHA1 Message Date
lcnr
292f0c599f only allow ConstEquate with feature(gce) 2022-09-29 12:32:22 +02:00
lcnr
9ccb851182 update fixme 2022-09-28 17:04:29 +02:00
Yuki Okushi
ae2028817a
Rollup merge of #102378 - compiler-errors:issue-102289, r=jackh726 
Use already resolved `self_ty` in `confirm_fn_pointer_candidate`

Fixes #102289
 2022-09-28 13:07:20 +09:00
Yuki Okushi
bf54cfe2b2
Rollup merge of #102348 - nnethercote:tweak-FulfillProcessor, r=jackh726 
Tweak `FulfillProcessor`.

Avoids some unnecessary references and lifetimes.

r? `@jackh726`
 2022-09-28 13:07:19 +09:00
Michael Goulet
e5776c6903 Use already resolved self_ty in confirm_fn_pointer_candidate 2022-09-27 20:00:24 +00:00
Nicholas Nethercote
b69c335327 Tweak FulfillProcessor. 
Avoids some unnecessary references and lifetimes.
 2022-09-27 16:37:00 +10:00
Pietro Albini
3975d55d98
remove cfg(bootstrap) 2022-09-26 10:14:45 +02:00
Matthias Krüger
16de1fddee
Rollup merge of #102016 - lcnr:given-OutlivesEnvironment, r=jackh726 
implied_bounds: deal with inference vars

fixes #101951

while computing implied bounds for `<<T as ConstructionFirm>::Builder as BuilderFn<'_>>::Output` normalization replaces a projection with an inference var (adding a `Projection` obligation). Until we prove that obligation, this inference var remains unknown, which caused us to miss an implied bound necessary to prove that the unnormalized projection from the trait method signature is wf.

r? types
 2022-09-25 09:32:07 +02:00
bors
d0ece44cfa Auto merge of #102040 - TaKO8Ki:separate-definitions-and-hir-owners, r=cjgillot 
Separate definitions and HIR owners in the type system

Fixes #83158

r? `@cjgillot`
 2022-09-24 22:42:07 +00:00
Takayuki Maeda
8fe936099a separate definitions and HIR owners 
fix a ui test

use `into`

fix clippy ui test

fix a run-make-fulldeps test

implement `IntoQueryParam<DefId>` for `OwnerId`

use `OwnerId` for more queries

change the type of `ParentOwnerIterator::Item` to `(OwnerId, OwnerNode)`
 2022-09-24 23:21:19 +09:00
Matthias Krüger
5fb41a6031
Rollup merge of #102204 - fee1-dead-contrib:manually-drop-trivially-drop, r=oli-obk 
Make `ManuallyDrop` satisfy `~const Destruct`
 2022-09-24 14:29:55 +02:00
Deadbeef
a74eba4ad5 Make ManuallyDrop satisfy ~const Destruct 2022-09-23 18:07:36 +00:00
bors
4a14677239 Auto merge of #102192 - matthiaskrgr:rollup-0ctjzco, r=matthiaskrgr 
Rollup of 7 pull requests

Successful merges:

 - #102094 (Add missing documentation for `bool::from_str`)
 - #102115 (Add examples to `bool::then` and `bool::then_some`)
 - #102134 (Detect panic strategy using `rustc --print cfg`)
 - #102137 (Don't convert valtree to constvalue during normalization)
 - #102148 (add regression test for miri issue 2433)
 - #102158 (rustdoc: clean up CSS/DOM for deprecation warnings)
 - #102177 (Fix a typo in `std`'s root docs)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
 2022-09-23 16:44:06 +00:00
Matthias Krüger
3a8bad98d7
Rollup merge of #102137 - b-naber:lazy-const-val-conversion, r=lcnr 
Don't convert valtree to constvalue during normalization

r? ``@lcnr``
 2022-09-23 15:40:22 +02:00
bors
9a963e3bad Auto merge of #102056 - b-naber:unevaluated, r=lcnr 
Introduce mir::Unevaluated

Previously the distinction between unevaluated constants in the type-system and in mir was not explicit and a little confusing. Probably better to introduce its own type for that.

r? `@lcnr`
 2022-09-23 13:39:11 +00:00
b-naber
a705e65605 rename Unevaluated to UnevaluatedConst 2022-09-23 14:27:34 +02:00
bors
89e4e1f1b3 Auto merge of #102139 - Dylan-DPC:rollup-ljlipt8, r=Dylan-DPC 
Rollup of 8 pull requests

Successful merges:

 - #101598 (Update rustc's information on Android's sanitizers)
 - #102036 (Remove use of `io::ErrorKind::Other` in std)
 - #102037 (Make cycle errors recoverable)
 - #102069 (Skip `Equate` relation in `handle_opaque_type`)
 - #102076 (rustc_transmute: fix big-endian discriminants)
 - #102107 (Add missing space between notable trait tooltip and where clause)
 - #102119 (Fix a typo “pararmeter” in error message)
 - #102131 (Added which number is computed in compute_float.)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
 2022-09-22 15:18:35 +00:00
Dylan DPC
d5ae6737bf
Rollup merge of #102037 - jyn514:normalize-docs, r=lcnr 
Make cycle errors recoverable

In particular, this allows rustdoc to recover from cycle errors when normalizing associated types for documentation.

In the past, ```@jackh726``` has said we need to be careful about overflow errors: https://github.com/rust-lang/rust/pull/91430#issuecomment-983997013

> Off the top of my head, we definitely should be careful about treating overflow errors the same as
"not implemented for some reason" errors. Otherwise, you could end up with behavior that is
different depending on recursion depth. But, that might be context-dependent.

But cycle errors should be safe to unconditionally report; they don't depend on the recursion depth, they will always be an error whenever they're encountered.

Helps with https://github.com/rust-lang/rust/issues/81091.

r? ```@lcnr``` cc ```@matthewjasper```
 2022-09-22 18:25:53 +05:30
bors
8ab71ab59f Auto merge of #100980 - compiler-errors:normalize-opaque-w-bound-vars, r=lcnr 
Normalize opaques w/ bound vars

First, we reenable normalization of opaque types with escaping late bound regions to fix rust-lang/miri#2433. This essentially reverts #89285.

Second, we mitigate the perf regression found in #88862 by simplifying the way that we relate (sub and eq) GeneratorWitness types.

This relies on the fact that we construct these GeneratorWitness types somewhat particularly (with all free regions found in the witness types replaced with late bound regions) -- but those bound regions really should be treated as existential regions, not universal ones. Those two facts leads me to believe that we do not need to use the full `higher_ranked_sub` machinery to relate two generator witnesses. I'm pretty confident that this is correct, but I'm glad to discuss this further.
 2022-09-22 12:47:31 +00:00
b-naber
a9e657dbfc don't convert valtree to constvalue during normalization 2022-09-22 14:46:14 +02:00
b-naber
9f3784df89 introduce mir::Unevaluated 2022-09-22 12:35:28 +02:00
bors
7a8636c843 Auto merge of #100982 - fee1-dead-contrib:const-impl-requires-const-trait, r=oli-obk 
Require `#[const_trait]` on `Trait` for `impl const Trait`

r? `@oli-obk`
 2022-09-22 04:22:24 +00:00
Michael Goulet
43119d6438 Normalize opaques with escaping bound vars 2022-09-22 02:17:39 +00:00
Jhonny Bill Mena
e52e2344dc FIX - adopt new Diagnostic naming in newly migrated modules 
FIX - ambiguous Diagnostic link in docs

UPDATE - rename diagnostic_items to IntoDiagnostic and AddToDiagnostic

[Gardening] FIX - formatting via `x fmt`

FIX - rebase conflicts. NOTE: Confirm wheather or not we want to handle TargetDataLayoutErrorsWrapper this way

DELETE - unneeded allow attributes in Handler method

FIX - broken test

FIX - Rebase conflict

UPDATE - rename residual _SessionDiagnostic and fix LintDiag link
 2022-09-21 11:43:22 -04:00
Jhonny Bill Mena
a3396b2070 UPDATE - rename DiagnosticHandler macro to Diagnostic 2022-09-21 11:39:53 -04:00
Jhonny Bill Mena
19b348fed4 UPDATE - rename DiagnosticHandler trait to IntoDiagnostic 2022-09-21 11:39:52 -04:00
Jhonny Bill Mena
5b8152807c UPDATE - move SessionDiagnostic from rustc_session to rustc_errors 2022-09-21 11:39:52 -04:00
bors
1de00d1ac5 Auto merge of #100096 - compiler-errors:fn-return-must-be-sized, r=jackh726 
a fn pointer doesn't implement `Fn`/`FnMut`/`FnOnce` if its return type isn't sized

I stumbled upon #83915 which hasn't received much attention recently, and I wanted to revive it since this is one existing soundness hole that seems pretty easy to fix.

I'm not actually sure that the [alternative approach described here](https://github.com/rust-lang/rust/pull/83915#issuecomment-823643322) is sufficient, given the `src/test/ui/function-pointer/unsized-ret.rs` example I provided below. Rebasing the branch mentioned in that comment and testing that UI test, it seems that we actually end up only observing that `str: !Sized` during monomorphization, whereupon we ICE. Even if we were to fix that ICE, ideally we'd be raising an error that a fn pointer is being used badly during _typecheck_ instead of monomorphization, hence adapting the original approach in #83915.

I am happy to close this if people would prefer we rebase the original PR and land that -- I am partly opening to be annoying and get people thinking about this unsoundness again ❤️ 😸

cc: `@estebank` and `@nikomatsakis`
r? types

Here's a link to the thread: https://rust-lang.zulipchat.com/#narrow/stream/144729-t-types/topic/PR.20.2383915/near/235421351 for more context.
 2022-09-21 04:35:20 +00:00
bors
cd8cc91045 Auto merge of #101989 - fee1-dead-contrib:const_trait_impl-assoc-caller-bounds, r=oli-obk 
make projection bounds with const bounds satisfy const

Fixes #101982.
 2022-09-20 16:24:36 +00:00
Joshua Nelson
1512ce5925 Make cycle errors recoverable 
In particular, this allows rustdoc to recover from cycle errors when normalizing associated types for documentation.

In the past, `@jackh726` has said we need to be careful about overflow errors:

> Off the top of my head, we definitely should be careful about treating overflow errors the same as
"not implemented for some reason" errors. Otherwise, you could end up with behavior that is
different depending on recursion depth. But, that might be context-dependent.

But cycle errors should be safe to unconditionally report; they don't depend on the recursion depth, they will always be an error whenever they're encountered.
 2022-09-19 22:14:40 -05:00
Joshua Nelson
749dec6451 Make OUT an associated type instead of a generic parameter 
This avoids toil when changing other functions in `ObligationForest` to take an `OUT` parameter.
 2022-09-19 22:14:39 -05:00
Joshua Nelson
5922d6cf60 slightly cleanup building SelectionContext 2022-09-19 22:14:39 -05:00
lcnr
71f8fd5c58 improve infer var handling for implied bounds 2022-09-19 15:13:34 +02:00
bors
11bb80a92b Auto merge of #101901 - lcnr:early-binder-type-foldable, r=compiler-errors 
`EarlyBinder` prevent misuse

folding a type before substituting is pretty much always wrong and could happen by accident, e.g. see https://github.com/rust-lang/rust/pull/99798#discussion_r968666538

this PR removes the `TypeFoldable` and `TypeVisitable` impl from `EarlyBinder`.

r? types cc `@jackh726`
 2022-09-19 10:35:09 +00:00
lcnr
647052fc04 remove the Subst trait, always use EarlyBinder 2022-09-19 11:37:27 +02:00
bors
503e19d01e Auto merge of #101629 - compiler-errors:issue-101623, r=sanxiyn 
Be careful about `expr_ty_adjusted` when noting block tail type

Fixes #101623
 2022-09-19 07:41:54 +00:00
bors
efa717bc2d Auto merge of #101924 - jackh726:revert-static-hrtb-error, r=compiler-errors 
Re-add HRTB implied static bug note

r? `@compiler-errors` since you reviewed it previously

I deleted a `normalize` call and forgot about it. Whoops.
 2022-09-19 04:56:14 +00:00
Deadbeef
ee96ae0a32 make projection bounds with const bounds satisfy const 2022-09-18 18:05:30 +00:00
Jack Huey
e7ca6e1b47 Use Predicate ConstraintCategory when normalizing 2022-09-17 11:46:05 -04:00
Dylan DPC
3ad81e0dd8
Rollup merge of #93628 - est31:stabilize_let_else, r=joshtriplett 
Stabilize `let else`

🎉  **Stabilizes the `let else` feature, added by [RFC 3137](https://github.com/rust-lang/rfcs/pull/3137).** 🎉

Reference PR: https://github.com/rust-lang/reference/pull/1156

closes #87335 (`let else` tracking issue)

FCP: https://github.com/rust-lang/rust/pull/93628#issuecomment-1029383585

----------

## Stabilization report

### Summary

The feature allows refutable patterns in `let` statements if the expression is
followed by a diverging `else`:

```Rust
fn get_count_item(s: &str) -> (u64, &str) {
    let mut it = s.split(' ');
    let (Some(count_str), Some(item)) = (it.next(), it.next()) else {
        panic!("Can't segment count item pair: '{s}'");
    };
    let Ok(count) = u64::from_str(count_str) else {
        panic!("Can't parse integer: '{count_str}'");
    };
    (count, item)
}
assert_eq!(get_count_item("3 chairs"), (3, "chairs"));
```

### Differences from the RFC / Desugaring

Outside of desugaring I'm not aware of any differences between the implementation and the RFC. The chosen desugaring has been changed from the RFC's [original](https://rust-lang.github.io/rfcs/3137-let-else.html#reference-level-explanations). You can read a detailed discussion of the implementation history of it in `@cormacrelf` 's [summary](https://github.com/rust-lang/rust/pull/93628#issuecomment-1041143670) in this thread, as well as the [followup](https://github.com/rust-lang/rust/pull/93628#issuecomment-1046598419). Since that followup, further changes have happened to the desugaring, in #98574, #99518, #99954. The later changes were mostly about the drop order: On match, temporaries drop in the same order as they would for a `let` declaration. On mismatch, temporaries drop before the `else` block.

### Test cases

In chronological order as they were merged.

Added by df9a2e0687 (#87688):

* [`ui/pattern/usefulness/top-level-alternation.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/pattern/usefulness/top-level-alternation.rs) to ensure the unreachable pattern lint visits patterns inside `let else`.

Added by 5b95df4bdc (#87688):

* [`ui/let-else/let-else-bool-binop-init.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-bool-binop-init.rs) to ensure that no lazy boolean expressions (using `&&` or `||`) are allowed in the expression, as the RFC mandates.
* [`ui/let-else/let-else-brace-before-else.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-brace-before-else.rs) to ensure that no `}` directly preceding the `else` is allowed in the expression, as the RFC mandates.
* [`ui/let-else/let-else-check.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-check.rs) to ensure that `#[allow(...)]` attributes added to the entire `let` statement apply for the `else` block.
* [`ui/let-else/let-else-irrefutable.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-irrefutable.rs) to ensure that the `irrefutable_let_patterns` lint fires.
* [`ui/let-else/let-else-missing-semicolon.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-missing-semicolon.rs) to ensure the presence of semicolons at the end of the `let` statement.
* [`ui/let-else/let-else-non-diverging.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-non-diverging.rs) to ensure the `else` block diverges.
* [`ui/let-else/let-else-run-pass.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-run-pass.rs) to ensure the feature works in some simple test case settings.
* [`ui/let-else/let-else-scope.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-scope.rs) to ensure the bindings created by the outer `let` expression are not available in the `else` block of it.

Added by bf7c32a447 (#89965):

* [`ui/let-else/issue-89960.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/issue-89960.rs) as a regression test for the ICE-on-error bug #89960 . Later in 102b9125e1 this got removed in favour of more comprehensive tests.

Added by 856541963c (#89974):

* [`ui/let-else/let-else-if.rs`](https://github.com/rust-lang/rust/blob/1.58.1/src/test/ui/let-else/let-else-if.rs) to test for the improved error message that points out that `let else if` is not possible.

Added by 9b45713b6c:

* [`ui/let-else/let-else-allow-unused.rs`](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-allow-unused.rs) as a regression test for #89807, to ensure that `#[allow(...)]` attributes added to the entire `let` statement apply for bindings created by the `let else` pattern.

Added by 61bcd8d307 (#89841):

* [`ui/let-else/let-else-non-copy.rs`](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-non-copy.rs) to ensure that a copy is performed out of non-copy wrapper types. This mirrors `if let` behaviour. The test case bases on rustc internal changes originally meant for #89933 but then removed from the PR due to the error prior to the improvements of #89841.
* [`ui/let-else/let-else-source-expr-nomove-pass.rs `](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-source-expr-nomove-pass.rs) to ensure that while there is a move of the binding in the successful case, the `else` case can still access the non-matching value. This mirrors `if let` behaviour.

Added by 102b9125e1 (#89841):

* [`ui/let-else/let-else-ref-bindings.rs`](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-ref-bindings.rs) and [`ui/let-else/let-else-ref-bindings-pass.rs `](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-ref-bindings-pass.rs) to check `ref` and `ref mut` keywords in the pattern work correctly and error when needed.

Added by 2715c5f984 (#89841):

* Match ergonomic tests adapted from the `rfc2005` test suite.

Added by fec8a507a2 (#89841):

* [`ui/let-else/let-else-deref-coercion-annotated.rs`](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-deref-coercion-annotated.rs) and [`ui/let-else/let-else-deref-coercion.rs`](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-deref-coercion.rs) to check deref coercions.

#### Added since this stabilization report was originally written (2022-02-09)

Added by 76ea566677 (#94211):

* [`ui/let-else/let-else-destructuring.rs`](https://github.com/rust-lang/rust/blob/1.63.0/src/test/ui/let-else/let-else-destructuring.rs) to give a nice error message if an user tries to do an assignment with a (possibly refutable) pattern and an `else` block, like asked for in #93995.

Added by e7730dcb7e (#94208):

* [`ui/let-else/let-else-allow-in-expr.rs`](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-allow-in-expr.rs) to test whether `#[allow(unused_variables)]` works in the expr, as well as its non presence, as well as putting it on the entire `let else` *affects* the expr, too. This was adding a missing test as pointed out by the stabilization report.
* Expansion of `ui/let-else/let-else-allow-unused.rs` and `ui/let-else/let-else-check.rs` to ensure that non-presence of `#[allow(unused)]` does issue the unused lint. This was adding a missing test case as pointed out by the stabilization report.

Added by 5bd71063b3 (#94208):

* [`ui/let-else/let-else-slicing-error.rs`](https://github.com/rust-lang/rust/blob/1.61.0/src/test/ui/let-else/let-else-slicing-error.rs), a regression test for #92069, which got fixed without addition of a regression test. This resolves a missing test as pointed out by the stabilization report.

Added by 5374688e1d (#98574):

* [`src/test/ui/async-await/async-await-let-else.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/async-await/async-await-let-else.rs) to test the interaction of async/await with `let else`

Added by 6c529ded86 (#98574):

* [`src/test/ui/let-else/let-else-temporary-lifetime.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/let-else/let-else-temporary-lifetime.rs) as a (partial) regression test for #98672

Added by 9b56640106 (#99518):

* [`src/test/ui/let-else/let-else-temp-borrowck.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/let-else/let-else-temporary-lifetime.rs) as a regression test for #93951
* Extension of `src/test/ui/let-else/let-else-temporary-lifetime.rs` to include a partial regression test for #98672 (especially regarding `else` drop order)

Added by baf9a7cb57 (#99518):

* Extension of `src/test/ui/let-else/let-else-temporary-lifetime.rs` to include a partial regression test for #93951, similar to `let-else-temp-borrowck.rs`

Added by 60be2de8b7 (#99518):

* Extension of `src/test/ui/let-else/let-else-temporary-lifetime.rs` to include a program that can now be compiled thanks to borrow checker implications of #99518

Added by 47a7a91c96 (#100132):

* [`src/test/ui/let-else/issue-100103.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/let-else/issue-100103.rs), as a regression test for #100103, to ensure that there is no ICE when doing `Err(...)?` inside else blocks.

Added by e3c5bd617d (#100443):

* [`src/test/ui/let-else/let-else-then-diverge.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/let-else/let-else-then-diverge.rs), to verify that there is no unreachable code error with the current desugaring.

Added by 981852677c (#100443):

* [`src/test/ui/let-else/issue-94176.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/let-else/issue-94176.rs), to make sure that a correct span is emitted for a missing trailing expression error. Regression test for #94176.

Added by e182d12a84 (#100434):

* [src/test/ui/unpretty/pretty-let-else.rs](https://github.com/rust-lang/rust/blob/master/src/test/ui/unpretty/pretty-let-else.rs), as a regression test to ensure pretty printing works for `let else` (this bug surfaced in many different ways)

Added by e26285603c (#99954):

* [`src/test/ui/let-else/let-else-temporary-lifetime.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/let-else/let-else-temporary-lifetime.rs) extended to contain & borrows as well, as this was identified as an earlier issue with the desugaring: https://github.com/rust-lang/rust/issues/98672#issuecomment-1200196921

Added by 2d8460ef43 (#99291):

* [`src/test/ui/let-else/let-else-drop-order.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/let-else/let-else-drop-order.rs) a matrix based test for various drop order behaviour of `let else`. Especially, it verifies equality of `let` and `let else` drop orders, [resolving](https://github.com/rust-lang/rust/pull/93628#issuecomment-1238498468) a [stabilization blocker](https://github.com/rust-lang/rust/pull/93628#issuecomment-1055738523).

Added by 1b87ce0d40 (#101410):

* Edit to `src/test/ui/let-else/let-else-temporary-lifetime.rs` to add the `-Zvalidate-mir` flag, as a regression test for #99228

Added by af591ebe4d (#101410):

* [`src/test/ui/let-else/issue-99975.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui/let-else/issue-99975.rs) as a regression test for the ICE #99975.

Added by this PR:

* `ui/let-else/let-else.rs`, a simple run-pass check, similar to `ui/let-else/let-else-run-pass.rs`.

### Things not currently tested

* ~~The `#[allow(...)]` tests check whether allow works, but they don't check whether the non-presence of allow causes a lint to fire.~~ → *test added by e7730dcb7eb29a10ee73f269f4dc6e9d606db0da*
* ~~There is no `#[allow(...)]` test for the expression, as there are tests for the pattern and the else block.~~ → *test added by e7730dcb7eb29a10ee73f269f4dc6e9d606db0da*
* ~~`let-else-brace-before-else.rs` forbids the `let ... = {} else {}` pattern and there is a rustfix to obtain `let ... = ({}) else {}`. I'm not sure whether the `.fixed` files are checked by the tooling that they compile. But if there is no such check, it would be neat to make sure that `let ... = ({}) else {}` compiles.~~ → *test added by e7730dcb7eb29a10ee73f269f4dc6e9d606db0da*
* ~~#92069 got closed as fixed, but no regression test was added. Not sure it's worth to add one.~~ → *test added by 5bd71063b3810d977aa376d1e6dd7cec359330cc*
* ~~consistency between `let else` and `if let` regarding lifetimes and drop order: https://github.com/rust-lang/rust/pull/93628#issuecomment-1055738523~~ → *test added by 2d8460ef43d902f34ba2133fe38f66ee8d2fdafc*

Edit: they are all tested now.

### Possible future work / Refutable destructuring assignments

[RFC 2909](https://rust-lang.github.io/rfcs/2909-destructuring-assignment.html) specifies destructuring assignment, allowing statements like `FooBar { a, b, c } = foo();`.
As it was stabilized, destructuring assignment only allows *irrefutable* patterns, which before the advent of `let else` were the only patterns that `let` supported.
So the combination of `let else` and destructuring assignments gives reason to think about extensions of the destructuring assignments feature that allow refutable patterns, discussed in #93995.

A naive mapping of `let else` to destructuring assignments in the form of `Some(v) = foo() else { ... };` might not be the ideal way. `let else` needs a diverging `else` clause as it introduces new bindings, while assignments have a default behaviour to fall back to if the pattern does not match, in the form of not performing the assignment. Thus, there is no good case to require divergence, or even an `else` clause at all, beyond the need for having *some* introducer syntax so that it is clear to readers that the assignment is not a given (enums and structs look similar). There are better candidates for introducer syntax however than an empty `else {}` clause, like `maybe` which could be added as a keyword on an edition boundary:

```Rust
let mut v = 0;
maybe Some(v) = foo(&v);
maybe Some(v) = foo(&v) else { bar() };
```

Further design discussion is left to an RFC, or the linked issue.
 2022-09-17 15:31:06 +05:30
bors
c524c7dd25 Auto merge of #98588 - b-naber:valtrees-cleanup, r=lcnr 
Use only ty::Unevaluated<'tcx, ()> in type system

r? `@lcnr`
 2022-09-17 03:04:22 +00:00
Jack Huey
e09242d5b8 Final bits 2022-09-16 17:47:53 -04:00
Jack Huey
9929c0ac76 Add AscribeUserTypeProvePredicate 2022-09-16 17:20:11 -04:00
bors
4d4e51e428 Auto merge of #101902 - jackh726:revert-static-hrtb-error, r=nikomatsakis 
Partially revert #101433

reverts #101433 to fix #101844

We should get this into the beta cut, since the ICE is getting hit quite a bit.
 2022-09-16 16:46:14 +00:00
Jack Huey
92b759f517 Revert "Better errors for implied static bound" 
This reverts commit c75817b0a7.
 2022-09-16 09:47:07 -04:00
Jack Huey
bba514b7b4 Revert "Use Predicate ConstraintCategory when normalizing" 
This reverts commit aae37f8763.
 2022-09-16 09:01:28 -04:00
bors
2d1aa57d1e Auto merge of #101860 - oli-obk:information_throwing, r=compiler-errors 
Don't throw away information just to recompute it again

also allows making some functions private.
 2022-09-16 09:57:32 +00:00
Deadbeef
77b0c47b82 Normalize param_env for trait assoc consts in typeck 2022-09-16 11:48:43 +08:00
Deadbeef
4231661789 Do not require const predicates to hold when checking if a projection type is wf 2022-09-16 11:48:42 +08:00
est31
173eb6f407 Only enable the let_else feature on bootstrap 
On later stages, the feature is already stable.

Result of running:

rg -l "feature.let_else" compiler/ src/librustdoc/ library/ | xargs sed -s -i "s#\\[feature.let_else#\\[cfg_attr\\(bootstrap, feature\\(let_else\\)#"
 2022-09-15 21:06:45 +02:00