Use parenthetical notation for `Fn` traits
Always use the `Fn(T) -> R` format when printing closure traits instead of `Fn<(T,), Output = R>`.
Address #67100:
```
error[E0277]: expected a `Fn()` closure, found `F`
--> file.rs:6:13
|
6 | call_fn(f)
| ------- ^ expected an `Fn()` closure, found `F`
| |
| required by a bound introduced by this call
|
= note: wrap the `F` in a closure with no arguments: `|| { /* code */ }`
note: required by a bound in `call_fn`
--> file.rs:1:15
|
1 | fn call_fn<F: Fn() -> ()>(f: &F) {
| ^^^^^^^^^^ required by this bound in `call_fn`
help: consider further restricting this bound
|
5 | fn call_any<F: std::any::Any + Fn()>(f: &F) {
| ++++++
```
Always use the `Fn(T) -> R` format when printing closure traits instead of `Fn<(T,), Output = R>`.
Fix#67100:
```
error[E0277]: expected a `Fn()` closure, found `F`
--> file.rs:6:13
|
6 | call_fn(f)
| ------- ^ expected an `Fn()` closure, found `F`
| |
| required by a bound introduced by this call
|
= note: wrap the `F` in a closure with no arguments: `|| { /* code */ }`
note: required by a bound in `call_fn`
--> file.rs:1:15
|
1 | fn call_fn<F: Fn() -> ()>(f: &F) {
| ^^^^^^^^^^ required by this bound in `call_fn`
help: consider further restricting this bound
|
5 | fn call_any<F: std::any::Any + Fn()>(f: &F) {
| ++++++
```
The guarded call will ICE on its own.
While this improved diagnostics in the presence of bugs somewhat, it is also a blocker to query feeding of constants. If this case is hit again, we should instead improve diagnostics of the root ICE
compiler: validate.rs belongs next to what it validates
It's hard to find code that is deeply nested and far away from its callsites, so let's move `rustc_const_eval::transform::validate` into `rustc_mir_transform`, where all of its callers are. As `rustc_mir_transform` already depends on `rustc_const_eval`, the added visible dependency edge doesn't mean the dependency tree got any worse.
This also lets us unnest the `check_consts` module.
I did look into moving everything inside `rustc_const_eval::transform` into `rustc_mir_transform`. It turned out to be a much more complex operation, with more concerns and real edges into the `const_eval` crate, whereas this was both faster and more obvious.
Run rustfmt on files that need it.
Somehow these files aren't properly formatted. By default `x fmt` and `x tidy` only check files that have changed against master, so if an ill-formatted file somehow slips in it can stay that way as long as it doesn't get modified(?)
I found these when I ran `x fmt` explicitly on every `.rs` file in the repo, while working on
https://github.com/rust-lang/compiler-team/issues/750.
Validate the special layout restriction on `DynMetadata`
If you look at <https://stdrs.dev/nightly/x86_64-unknown-linux-gnu/std/ptr/struct.DynMetadata.html>, you'd think that `DynMetadata` is a struct with fields.
But it's actually not, because the lang item is special-cased in rustc_middle layout:
7601adcc76/compiler/rustc_middle/src/ty/layout.rs (L861-L864)
That explains the very confusing codegen ICEs I was getting in https://github.com/rust-lang/rust/pull/124251#issuecomment-2128543265
> Tried to extract_field 0 from primitive OperandRef(Immediate((ptr: %5 = load ptr, ptr %4, align 8, !nonnull !3, !align !5, !noundef !3)) @ TyAndLayout { ty: DynMetadata<dyn Callsite>, layout: Layout { size: Size(8 bytes), align: AbiAndPrefAlign { abi: Align(8 bytes), pref: Align(8 bytes) }, abi: Scalar(Initialized { value: Pointer(AddressSpace(0)), valid_range: 1..=18446744073709551615 }), fields: Primitive, largest_niche: Some(Niche { offset: Size(0 bytes), value: Pointer(AddressSpace(0)), valid_range: 1..=18446744073709551615 }), variants: Single { index: 0 }, max_repr_align: None, unadjusted_abi_align: Align(8 bytes) } })
because there was a `Field` projection despite the layout clearly saying it's [`Primitive`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_target/abi/enum.FieldsShape.html#variant.Primitive).
Thus this PR updates the MIR validator to check for such a projection, and changes `libcore` to not ever emit any projections into `DynMetadata`, just to transmute the whole thing when it wants a pointer.
Somehow these files aren't properly formatted. By default `x fmt` and `x
tidy` only check files that have changed against master, so if an
ill-formatted file somehow slips in it can stay that way as long as it
doesn't get modified(?)
I found these when I ran `x fmt` explicitly on every `.rs` file in the
repo, while working on
https://github.com/rust-lang/compiler-team/issues/750.
Remove more `#[macro_use] extern crate tracing`
Because explicit importing of macros via use items is nicer (more standard and readable) than implicit importing via `#[macro_use]`. Continuing the work from #124511 and #124914.
r? `@jackh726`
offset: allow zero-byte offset on arbitrary pointers
As per prior `@rust-lang/opsem` [discussion](https://github.com/rust-lang/opsem-team/issues/10) and [FCP](https://github.com/rust-lang/unsafe-code-guidelines/issues/472#issuecomment-1793409130):
- Zero-sized reads and writes are allowed on all sufficiently aligned pointers, including the null pointer
- Inbounds-offset-by-zero is allowed on all pointers, including the null pointer
- `offset_from` on two pointers derived from the same allocation is always allowed when they have the same address
This removes surprising UB (in particular, even C++ allows "nullptr + 0", which we currently disallow), and it brings us one step closer to an important theoretical property for our semantics ("provenance monotonicity": if operations are valid on bytes without provenance, then adding provenance can't make them invalid).
The minimum LLVM we require (v17) includes https://reviews.llvm.org/D154051, so we can finally implement this.
The `offset_from` change is needed to maintain the equivalence with `offset`: if `let ptr2 = ptr1.offset(N)` is well-defined, then `ptr2.offset_from(ptr1)` should be well-defined and return N. Now consider the case where N is 0 and `ptr1` dangles: we want to still allow offset_from here.
I think we should change offset_from further, but that's a separate discussion.
Fixes https://github.com/rust-lang/rust/issues/65108
[Tracking issue](https://github.com/rust-lang/rust/issues/117945) | [T-lang summary](https://github.com/rust-lang/rust/pull/117329#issuecomment-1951981106)
Cc `@nikic`
Rename some `FulfillmentErrorCode`/`ObligationCauseCode` variants to be less redundant
1. Rename some `FulfillmentErrorCode` variants.
2. Always use `ObligationCauseCode::` to prefix a code, rather than using a glob import and naming them through `traits::`.
3. Rename some `ObligationCauseCode` variants -- I wasn't particularly thorough with thinking of a new names for these, so could workshop them if necessary.
4. Misc stuff from renaming.
r? lcnr
Rollup of 3 pull requests
Successful merges:
- #124003 (Dellvmize some intrinsics (use `u32` instead of `Self` in some integer intrinsics))
- #124169 (Don't fatal when calling `expect_one_of` when recovering arg in `parse_seq`)
- #124286 (Subtree sync for rustc_codegen_cranelift)
r? `@ghost`
`@rustbot` modify labels: rollup
Dellvmize some intrinsics (use `u32` instead of `Self` in some integer intrinsics)
This implements https://github.com/rust-lang/compiler-team/issues/693 minus what was implemented in #123226.
Note: I decided to _not_ change `shl`/... builder methods, as it just doesn't seem worth it.
r? ``@scottmcm``
deref patterns: lower deref patterns to MIR
This lowers deref patterns to MIR. This is a bit tricky because this is the first kind of pattern that requires storing a value in a temporary. Thanks to https://github.com/rust-lang/rust/pull/123324 false edges are no longer a problem.
The thing I'm not confident about is the handling of fake borrows. This PR ignores any fake borrows inside a deref pattern. We are guaranteed to at least fake borrow the place of the first pointer value, which could be enough, but I'm not certain.
Add simple async drop glue generation
This is a prototype of the async drop glue generation for some simple types. Async drop glue is intended to behave very similar to the regular drop glue except for being asynchronous. Currently it does not execute synchronous drops but only calls user implementations of `AsyncDrop::async_drop` associative function and awaits the returned future. It is not complete as it only recurses into arrays, slices, tuples, and structs and does not have same sensible restrictions as the old `Drop` trait implementation like having the same bounds as the type definition, while code assumes their existence (requires a future work).
This current design uses a workaround as it does not create any custom async destructor state machine types for ADTs, but instead uses types defined in the std library called future combinators (deferred_async_drop, chain, ready_unit).
Also I recommend reading my [explainer](https://zetanumbers.github.io/book/async-drop-design.html).
This is a part of the [MCP: Low level components for async drop](https://github.com/rust-lang/compiler-team/issues/727) work.
Feature completeness:
- [x] `AsyncDrop` trait
- [ ] `async_drop_in_place_raw`/async drop glue generation support for
- [x] Trivially destructible types (integers, bools, floats, string slices, pointers, references, etc.)
- [x] Arrays and slices (array pointer is unsized into slice pointer)
- [x] ADTs (enums, structs, unions)
- [x] tuple-like types (tuples, closures)
- [ ] Dynamic types (`dyn Trait`, see explainer's [proposed design](https://github.com/zetanumbers/posts/blob/main/async-drop-design.md#async-drop-glue-for-dyn-trait))
- [ ] coroutines (https://github.com/rust-lang/rust/pull/123948)
- [x] Async drop glue includes sync drop glue code
- [x] Cleanup branch generation for `async_drop_in_place_raw`
- [ ] Union rejects non-trivially async destructible fields
- [ ] `AsyncDrop` implementation requires same bounds as type definition
- [ ] Skip trivially destructible fields (optimization)
- [ ] New [`TyKind::AdtAsyncDestructor`](https://github.com/zetanumbers/posts/blob/main/async-drop-design.md#adt-async-destructor-types) and get rid of combinators
- [ ] [Synchronously undroppable types](https://github.com/zetanumbers/posts/blob/main/async-drop-design.md#exclusively-async-drop)
- [ ] Automatic async drop at the end of the scope in async context
Delay interning errors to after validation
fixes https://github.com/rust-lang/rust/issues/122398fixes#122548
This improves diagnostics since validation errors are usually more helpful compared with interning errors that just make broad statements about the entire constant
r? `@RalfJung`
interpret: pass MemoryKind to adjust_alloc_base_pointer
Another puzzle piece for https://github.com/rust-lang/miri/pull/3475.
The 2nd commit renames base_pointer -> root_pointer; that's how Tree Borrows already calls them and I think the term is more clear than "base pointer". In particular, this distinguishes it from "base address", since a root pointer can point anywhere into an allocation, not just its base address.
https://github.com/rust-lang/rust/pull/124018 has been rolled up already so I couldn't add it there any more.
r? ```@oli-obk```
Taint const qualifs if a static is referenced that didn't pass wfcheck
It is correct to only check the signature here, as the ICE is caused by `USE_WITH_ERROR` trying to allocate memory to store the result of `WITH_ERROR` before evaluating it.
fixes#123153
interpret: remove outdated comment
In https://github.com/rust-lang/rust/pull/107756, allocation became generally fallible, so the "only panic if there is provenance" no longer applies.
r? ``@oli-obk``
Check `x86_64` size assertions on `aarch64`, too
(Context: https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Checking.20size.20assertions.20on.20aarch64.3F)
Currently the compiler has around 30 sets of `static_assert_size!` for various size-critical data structures (e.g. various IR nodes), guarded by `#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]`.
(Presumably this cfg avoids having to maintain separate size values for 32-bit targets and unusual 64-bit targets. Apparently it may have been necessary before the i128/u128 alignment changes, too.)
This is slightly incovenient for people on aarch64 workstations (e.g. Macs), because the assertions normally aren't checked until we push to a PR. So this PR adds `aarch64` to the `#[cfg(..)]` guarding all of those assertions in the compiler.
---
Implemented with a simple find/replace. Verified by manually inspecting each `static_assert_size!` in `compiler/`, and checking that either the replacement succeeded, or adding aarch64 wouldn't have been appropriate.
rename ptr::from_exposed_addr -> ptr::with_exposed_provenance
As discussed on [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/136281-t-opsem/topic/To.20expose.20or.20not.20to.20expose/near/427757066).
The old name, `from_exposed_addr`, makes little sense as it's not the address that is exposed, it's the provenance. (`ptr.expose_addr()` stays unchanged as we haven't found a better option yet. The intended interpretation is "expose the provenance and return the address".)
The new name nicely matches `ptr::without_provenance`.
Add `Ord::cmp` for primitives as a `BinOp` in MIR
Update: most of this OP was written months ago. See https://github.com/rust-lang/rust/pull/118310#issuecomment-2016940014 below for where we got to recently that made it ready for review.
---
There are dozens of reasonable ways to implement `Ord::cmp` for integers using comparison, bit-ops, and branches. Those differences are irrelevant at the rust level, however, so we can make things better by adding `BinOp::Cmp` at the MIR level:
1. Exactly how to implement it is left up to the backends, so LLVM can use whatever pattern its optimizer best recognizes and cranelift can use whichever pattern codegens the fastest.
2. By not inlining those details for every use of `cmp`, we drastically reduce the amount of MIR generated for `derive`d `PartialOrd`, while also making it more amenable to MIR-level optimizations.
Having extremely careful `if` ordering to μoptimize resource usage on broadwell (#63767) is great, but it really feels to me like libcore is the wrong place to put that logic. Similarly, using subtraction [tricks](https://graphics.stanford.edu/~seander/bithacks.html#CopyIntegerSign) (#105840) is arguably even nicer, but depends on the optimizer understanding it (https://github.com/llvm/llvm-project/issues/73417) to be practical. Or maybe [bitor is better than add](https://discourse.llvm.org/t/representing-in-ir/67369/2?u=scottmcm)? But maybe only on a future version that [has `or disjoint` support](https://discourse.llvm.org/t/rfc-add-or-disjoint-flag/75036?u=scottmcm)? And just because one of those forms happens to be good for LLVM, there's no guarantee that it'd be the same form that GCC or Cranelift would rather see -- especially given their very different optimizers. Not to mention that if LLVM gets a spaceship intrinsic -- [which it should](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Suboptimal.20inlining.20in.20std.20function.20.60binary_search.60/near/404250586) -- we'll need at least a rustc intrinsic to be able to call it.
As for simplifying it in Rust, we now regularly inline `{integer}::partial_cmp`, but it's quite a large amount of IR. The best way to see that is with 8811efa88b (diff-d134c32d028fbe2bf835fef2df9aca9d13332dd82284ff21ee7ebf717bfa4765R113) -- I added a new pre-codegen MIR test for a simple 3-tuple struct, and this PR change it from 36 locals and 26 basic blocks down to 24 locals and 8 basic blocks. Even better, as soon as the construct-`Some`-then-match-it-in-same-BB noise is cleaned up, this'll expose the `Cmp == 0` branches clearly in MIR, so that an InstCombine (#105808) can simplify that to just a `BinOp::Eq` and thus fix some of our generated code perf issues. (Tracking that through today's `if a < b { Less } else if a == b { Equal } else { Greater }` would be *much* harder.)
---
r? `@ghost`
But first I should check that perf is ok with this
~~...and my true nemesis, tidy.~~
