Document & implement the transmutation modeled by `BikeshedIntrinsicFrom`
Documents that `BikeshedIntrinsicFrom` models transmute-via-union, which is slightly more expressive than the transmute-via-cast implemented by `transmute_copy`. Additionally, we provide an implementation of transmute-via-union as a method on the `BikeshedIntrinsicFrom` trait with additional documentation on the boundary between trait invariants and caller obligations.
Whether or not transmute-via-union is the right kind of transmute to model remains up for discussion [1]. Regardless, it seems wise to document the present behavior.
[1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20'kind'.20of.20transmute.20to.20model.3F/near/426331967
Tracking Issue: https://github.com/rust-lang/rust/issues/99571
r? `@compiler-errors`
cc `@scottmcm,` `@Lokathor`
Add `#[warn(unreachable_pub)]` to a bunch of compiler crates
By default `unreachable_pub` identifies things that need not be `pub` and tells you to make them `pub(crate)`. But sometimes those things don't need any kind of visibility. So they way I did these was to remove the visibility entirely for each thing the lint identifies, and then add `pub(crate)` back in everywhere the compiler said it was necessary. (Or occasionally `pub(super)` when context suggested that was appropriate.) Tedious, but results in more `pub` removal.
There are plenty more crates to do but this seems like enough for a first PR.
r? `@compiler-errors`
Tie `impl_trait_overcaptures` lint to Rust 2024
The `impl_trait_overcaptures` lint is part of the migration to Rust 2024 and the Lifetime Capture Rules 2024. Now that we've stabilized precise capturing (RFC 3617), let's tie this lint to the `rust_2024_compatibility` lint group.
Tracking:
- https://github.com/rust-lang/rust/issues/117587
r? `@compiler-errors`
mv `build_reduced_graph_for_external_crate_res` into Resolver
`build_reduced_graph_for_external_crate_res` is only related to `Resolver`, so move it there.
r? `@petrochenkov`
const checking: properly compute the set of transient locals
For const-checking the MIR of a const/static initializer, we have to know the set of "transient" locals. The reason for this is that creating a mutable (or interior mutable) reference to a transient local is "safe" in the sense that this reference cannot possibly end up in the final value of the const -- even if it is turned into a raw pointer and stored in a union, we will see that pointer during interning and reliably reject it as dangling.
So far, we determined the set of transient locals as "locals that have a `StorageDead` somewhere". But that's not quite right -- if we had MIR like
```rust
StorageLive(_5);
StorageDead(_5);
StorageLive(_5);
// no further storage annotations for _5
```
Then we'd consider `_5` to be "transient", but it is not actually transient.
We do not currently generate such MIR, but I feel uneasy relying on subtle invariants like this. So this PR implements a proper analysis for computing the set of "transient" locals: a local is "transient" if it is guaranteed dead at all `Return` terminators.
Cc `@cjgillot`
The `impl_trait_overcaptures` lint is part of the migration to Rust
2024 and the Lifetime Capture Rules 2024. Now that we've stabilized
precise capturing (RFC 3617), let's tie this lint to the
`rust_2024_compatibility` lint group.
add back test for stable-const-can-only-call-stable-const
This got accidentally removed in https://github.com/rust-lang/rust/pull/128596 (file `tests/ui/internal/internal-unstable-const.rs`). The test has little to do with "allow internal unstable" though, so add it in a file that already tests various const stability things.
Also tweak the help that suggests to add `rustc_allow_const_fn_unstable` to make it clear that this needs team approval, since it is a fairly big gun.
Use `FxHasher` on new solver unconditionally
r? lqd
This should actually fix the inference problem in ad855fe6db, since `HashSet::default` was not inferring the hasher when `HashSet` was coming from the stdlib due to the way that defaulted types/inference vars work. You could cherry-pick this on top of your PR alternatively.
rustdoc: clean up tuple <-> primitive conversion docs
This adds a minor missing feature to `fake_variadic`, so that it can render `impl From<(T,)> for [T; 1]` correctly.
Remove redundant flags from `lower_ty_common` that can be inferred from the HIR
...and then get rid of `lower_ty_common`.
r? ``@fmease`` or re-roll if you're busy!
Use subtyping for `UnsafeFnPointer` coercion, too
I overlooked this in #129059, which changed MIR typechecking to use subtyping for other fn pointer coercions.
Fixes#129285
Make `rustc_type_ir` build on stable
This PR fixes a handful of issues that appear in `rustc_type_ir` when trying to build the new solver on stable.
r? ```@compiler-errors```
```@bors``` rollup
library: Move unstable API of new_uninit to new features
- `new_zeroed` variants move to `new_zeroed_alloc`
- the `write` fn moves to `box_uninit_write`
The remainder will be stabilized in upcoming patches, as it was decided to only stabilize `uninit*` and `assume_init`.
Print the generic parameter along with the variance in dumps.
This allows to make sure we are testing what we think we are testing.
While the tests are correct, I discovered that opaque duplicated args are in the reverse declaration order.
Add a special case for `CStr`/`CString` in the `improper_ctypes` lint
Revives #120176. Just needed to bless a test and fix an argument, but seemed reasonable to me otherwise.
Instead of saying to "consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct", we now tell users to "Use `*const ffi::c_char` instead, and pass the value from `CStr::as_ptr()`" when the type involved is a `CStr` or a `CString`.
The suggestion is not made for `&mut CString` or `*mut CString`.
r? ``````@cjgillot`````` (since you were the reviewer of the original PR #120176, but feel free to reroll)
Detect `*` operator on `!Sized` expression
The suggestion is new:
```
error[E0277]: the size for values of type `str` cannot be known at compilation time
--> $DIR/unsized-str-in-return-expr-arg-and-local.rs:15:9
|
LL | let x = *"";
| ^ doesn't have a size known at compile-time
|
= help: the trait `Sized` is not implemented for `str`
= note: all local variables must have a statically known size
= help: unsized locals are gated as an unstable feature
help: references to `!Sized` types like `&str` are `Sized`; consider not dereferencing the expression
|
LL - let x = *"";
LL + let x = "";
|
```
Fix#128199.
