interpret: make isize::MAX the limit for dynamic value sizes
We are currently enforcing `data_layout.obj_size_bound()` as the maximal dynamic size of a Rust value (including for `size_of_val_raw`), but that does not match the docs.
In particular, Miri currently falsely says that this code has UB:
```rust
#![feature(layout_for_ptr)]
fn main() {
let size = isize::MAX as usize;
// Creating a raw slice of size isize::MAX and asking for its size is okay.
let s = std::ptr::slice_from_raw_parts(1usize as *const u8, size);
assert_eq!(size, unsafe { std::mem::size_of_val_raw(s) });
}
```
Better suggestions for `Fn`-family trait selection errors
1. Suppress suggestions to add `std::ops::Fn{,Mut,Once}` bounds when a type already implements `Fn{,Mut,Once}`
2. Add a note that points out that a type does in fact implement `Fn{,Mut,Once}`, but the arguments vary (either by number or by actual arguments)
3. Add a note that points out that a type does in fact implement `Fn{,Mut,Once}`, but not the right one (e.g. implements `FnMut`, but `Fn` is required).
Fixes#95147
Specialize infinite-type "insert some indirection" suggestion for Option
Suggest `Option<Box<_>>` instead of `Box<Option<_>>` for infinitely-recursive members of a struct.
Not sure if I can get the span of the generic subty of the Option so I can make this a `+++`-style suggestion. The current output is a tiny bit less fancy looking than the original suggestion.
Should I limit the specialization to just `Option<Box<TheOuterStruct>>`? Because right now it applies to all `Option` members in the struct that are returned by `Representability::SelfRecursive`.
Fixes#91402
r? `@estebank`
(since you wrote the original suggestion and are definitely most familiar with it!)
Make lowering pull-based
~Based on https://github.com/rust-lang/rust/pull/90451~
Part of https://github.com/rust-lang/rust/pull/88186
The current lowering code visits all the item-likes in the AST in order, and lowers them one by one.
This PR changes it to index the AST and then proceed to lowering on-demand. This is closer to the logic of query-based lowering.
allow large Size again
This basically reverts most of https://github.com/rust-lang/rust/pull/80042, and instead does the panic in `bits()` with a `#[cold]` function to make sure it does not get inlined.
https://github.com/rust-lang/rust/pull/80042 added a comment about an invariant ("The top 3 bits are ALWAYS zero") that is not actually enforced, and if it were enforced that would be a problem for https://github.com/rust-lang/rust/pull/95388. So I think we should not have that invariant, and I adjusted the code accordingly.
r? `@oli-obk` Cc `@sivadeilra`
It's only used in one place, and there we clone and then make a bunch of
modifications. It's clearer if we duplicate more explicitly, and there's
a symmetry now between `sequence()` and `empty_sequence()`.
`parse_tt` needs a way to get from within submatchers make to the
enclosing submatchers. Currently it has two distinct mechanisms for
this:
- `Delimited` submatchers use `MatcherPos::stack` to record stuff about
the parent (and further back ancestors).
- `Sequence` submatchers use `MatcherPosSequence::parent` to point to
the parent matcher position.
Having two mechanisms is really confusing, and it took me a long time to
understand all this.
This commit eliminates `MatcherPos::stack`, and changes `Delimited`
submatchers to use the same mechanism as sequence submatchers. That
mechanism is also changed a bit: instead of storing the entire parent
`MatcherPos`, we now only store the necessary parts from the parent
`MatcherPos`.
Overall this is a small performance win, with the positives outweighing
the negatives, but it's mostly for clarity.
Spellchecking compiler comments
This PR cleans up the rest of the spelling mistakes in the compiler comments. This PR does not change any literal or code spelling issues.
Don't ICE when opaque types get their hidden type constrained again.
Contrary to popular belief, `codegen_fulfill_obligation` does not get used solely in codegen, so we cannot rely on `param_env` being set to RevealAll and thus revealing the hidden types instead of constraining them.
Fixes#89312 (for real this time)
Restore `impl Future<Output = Type>` to async blocks
I was sad when I undid some of the code I wrote in #91096 in the PR #95225, so I fixed it here to not print `[async output]`.
This PR "manually" normalizes the associated type `<[generator] as Generator>::Return` type which appears very frequently in `impl Future` types that result from async block desugaring.
Currently, we detect an exit from a `Delimited` submatcher when `idx`
exceeds the bounds of the current submatcher *and* there is a `stack`
entry.
This commit changes it to something simpler: just look for a
`CloseDelim` token.
Rollup of 6 pull requests
Successful merges:
- #93901 (Stabilize native library modifier syntax and the `whole-archive` modifier specifically)
- #94806 (Fix `cargo run tidy`)
- #94869 (Add the generic_associated_types_extended feature)
- #95011 (async: Give predictable name to binding generated from .await expressions.)
- #95251 (Reduce max hash in raw strings from u16 to u8)
- #95298 (Fix double drop of allocator in IntoIter impl of Vec)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
async: Give predictable name to binding generated from .await expressions.
This name makes it to debuginfo and allows debuggers to identify such bindings and their captured versions in suspended async fns.
This will be useful for async stack traces, as discussed in https://internals.rust-lang.org/t/async-debugging-logical-stack-traces-setting-goals-collecting-examples/15547.
I don't know if this needs some discussion by ````@rust-lang/compiler,```` e.g. about the name of the binding (`__awaitee`) or about the fact that this PR introduces a (soft) guarantee about a compiler generated name. Although, regarding the later, I think the same reasoning applies here as it does for debuginfo in general.
r? ````@tmandry````
Add the generic_associated_types_extended feature
Right now, this only ignore obligations that reference new placeholders in `poly_project_and_unify_type`. In the future, this might do other things, like allowing object-safe GATs.
**This feature is *incomplete* and quite likely unsound. This is mostly just for testing out potential future APIs using a "relaxed" set of rules until we figure out *proper* rules.**
Also drive by cleanup of adding a `ProjectAndUnifyResult` enum instead of using a `Result<Result<Option>>`.
r? `@nikomatsakis`
Remember mutability in `DefKind::Static`.
This allows to compute the `BodyOwnerKind` from `DefKind` only, and
removes a direct dependency of some MIR queries onto HIR.
As a side effect, it also simplifies metadata, since we don't need 4
flavours of `EntryKind::*Static` any more.
