I was looking into `array::IntoIter` optimization, and noticed that it wasn't annotating the loads with `noundef` for simple things like `array::IntoIter<i32, N>`.
Turned out to be a more general problem as `MaybeUninit::assume_init_read` isn't marking the load as initialized (<https://rust.godbolt.org/z/Mxd8TPTnv>), which is unfortunate since that's basically its reason to exist.
This PR lowers `ptr::read(p)` to `copy *p` in MIR, which fortuitiously also improves the IR we give to LLVM for things like `mem::replace`.
Don't even try to combine consts with incompatible types
~I left a more detailed explanation for why this fixes this issue in the UI test, but in general, we should not try to unify const infer vars and rigid consts if they have incompatible types. That's because we don't want something like a `ConstArgHasType` predicate to suddenly go from passing to failing, or vice versa, due to a shallow resolve.~
1. Use the `type_of` for a parameter in `try_eval_lit_or_param`, instead of the "expected" type from a `WithOptConstParam` def id.
2. Don't combine consts that have incompatible types.
Fixes#108781
feat: implement better error for manual impl of `Fn*` traits
Fixes#39259
cc `@estebank` (you gave me some advice in the linked issue, would you like to review?)
Do not ICE when we have fn pointer `Fn` obligations with bound vars in the self type
We never supported solving `for<'a> fn(&'a ()): Fn(&'a ())` -- I tried to add that support in #104929, but iirc `@lcnr` wanted to support this more generally by eagerly instantiating trait predicate binders with placeholders. That never happened due to blockers in the old solver, but we probably shouldn't ICE in any case.
On the bright side, this passes on the new solver :^)
Emit alias-eq when equating numeric var and projection
This doesn't fix everything having to do with projections and infer vars, but it does fix a common case I saw in HIR typeck.
r? `@lcnr`
Introduce a no-op `PlaceMention` statement for `let _ =`.
Fixes https://github.com/rust-lang/rust/issues/54003
Fixes https://github.com/rust-lang/rust/issues/80059
Split from https://github.com/rust-lang/rust/pull/101500
This PR introduces a new `PlaceMention` statement dedicated to matches that neither introduce bindings nor ascribe types. Without this, all traces of the match would vanish from MIR, making it impossible to diagnose unsafety or use in #101500.
This allows to mark `let _ = <unsafe union access or dereference>` as requiring an unsafe block.
Nominating for lang team, as this introduces an extra error.
feat/refactor: improve errors in case of ident with number at start
Improve parser code when we parse a integer (or float) literal but expect an identifier. We emit an error message saying that identifiers can't begin with numbers. This PR just improves that code and expands it to all identifiers. Note that I haven't implemented error recovery (this didn't exist before anyway), I might do that in a follow up PR.
Rollup of 8 pull requests
Successful merges:
- #108754 (Retry `pred_known_to_hold_modulo_regions` with fulfillment if ambiguous)
- #108759 (1.41.1 supported 32-bit Apple targets)
- #108839 (Canonicalize root var when making response from new solver)
- #108856 (Remove DropAndReplace terminator)
- #108882 (Tweak E0740)
- #108898 (Set `LIBC_CHECK_CFG=1` when building Rust code in bootstrap)
- #108911 (Improve rustdoc-gui/tester.js code a bit)
- #108916 (Remove an unused return value in `rustc_hir_typeck`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Canonicalize root var when making response from new solver
During trait solving, if we equate two inference variables `?0` and `?1` but don't equate them with any rigid types, then `InferCtxt::probe_ty_var` will return `Err` for both of these. The canonicalizer code will then canonicalize the variables independently(!), and the response will not reflect the fact that these two variables have been made equal.
This hinders inference and I also don't think it's sound? I haven't thought too much about it past that, so let's talk about it.
r? ``@lcnr``
Suppress copy impl error when post-normalized type references errors
Suppress spurious errors from the `Copy` impl validity check when fields have bad types *post*-normalization, instead of just pre-normalization.
----
The const-generics test regressed recently due to #107965, cc `````@BoxyUwU.`````
* I think it's because `[_; 0u32]: Copy` now fails to hold because a nested obligation `ConstArgHasType(0u32, usize)` fails.
* It's interesting that `[const_error]` shows up in the type only after normalization, though, but I'm pretty sure that it's due to the evaluate call that happens when normalizing unevaluated consts.
always resolve to universal regions if possible
`RegionConstraintCollector::opportunistic_resolve_var`, which is used in canonicalization and projection logic, doesn't resolve the region var to an equal universal region. So if we have equated `'static == '1 == '2`, it doesn't resolve `'1` or `'2` to `'static`. Now it does!
Addresses review comment https://github.com/rust-lang/rust/pull/107376#discussion_r1093233687.
r? `@lcnr`
Account for binders correctly when adding default RPITIT method assumption
As of #108203, we install extra projection predicates into the param-env of a default trait method when it has return-position `impl Trait` (or is async).
The implementation didn't account for the fact that it's walking into and out of binders, so we just need to shift all the debruijn indices accordingly when constructing the projection predicates.
Fixes#108579
r? types
Rollup of 7 pull requests
Successful merges:
- #108619 (Remove the option to disable `llvm-version-check`)
- #108728 (infer: fix and improve comments)
- #108731 (feat: impl better help for `.poll()` not found on `impl Future`)
- #108774 (Greatly improve the error messages when `run-make/translation` fails)
- #108805 (Update askama to 0.12 and improve whitespace control)
- #108823 (Add tracking issue for cf-protection to unstable book)
- #108855 (Custom MIR: Support `as` casts)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
feat: impl better help for `.poll()` not found on `impl Future`
Partially address #108572
I'd like to also address suggestions for generalized `Self` parameters as well. That'll be a separate PR.
Use `nuw` when calculating slice lengths from `Range`s
An `assume` would definitely not be worth it, but since the flag is almost free we might as well tell LLVM this, especially on `_unchecked` calls where there's no obvious way for it to deduce it.
(Today neither safe nor unsafe indexing gets it: <https://rust.godbolt.org/z/G1jYT548s>)
fix multiple issues when promoting type-test subject
Multiple interdependent fixes. See linked issues for a short description of each.
When Promoting a type-test `T: 'a` from within the closure back to its parent function, there are a couple pre-existing bugs and limitations. They were exposed by the recent changes to opaque types because the type-test subject (`T`) is no longer a simple ParamTy.
Commit 1:
Fixes#108635Fixes#107426
Commit 2:
Fixes#108639
Commit 3:
Fixes#107516
Do not ICE when failing to normalize in ConstProp.
There is no reason to delay a bug there, as we bubble up the failure as TooGeneric.
Fixes https://github.com/rust-lang/rust/issues/97728
Add regression tests for issue 70919
Desugaring DropAndReplace at MIR build (#107844) fixed#70919.
Add regressions tests, borrowed from #102078, to ensure we check for this in the future.
cc ``@Aaron1011``
const_eval: `implies_by` in `rustc_const_unstable`
Fixes#107605.
Extend support for `implies_by` (from `#[stable]` and `#[unstable]`) to `#[rustc_const_stable]` and `#[rustc_const_unstable]`.
cc ``@steffahn``
