Account for common `impl Trait`/`dyn Trait` return type errors
- When all return paths have the same type, suggest `impl Trait`.
- When all return paths implement the expected `trait`, suggest `Box<dyn Trait>` and mention using an `enum`.
- When multiple different types are returned and `impl Trait` is expected, extend the explanation.
- When return type is `impl Trait` and the return paths do not implement `Trait`, point at the returned values.
- Split `src/librustc/traits/error_reporting.rs` into multiple files to keep size under control.
Fix#68110, cc #66523.
Implement `DebugStruct::non_exhaustive`.
This patch adds a function (finish_non_exhaustive) to add ellipsis before the closing brace when formatting using `DebugStruct`.
## Example
```rust
#![feature(debug_non_exhaustive)]
use std::fmt;
struct Bar {
bar: i32,
hidden: f32,
}
impl fmt::Debug for Bar {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("Bar")
.field("bar", &self.bar)
.non_exhaustive(true) // Show that some other field(s) exist.
.finish()
}
}
assert_eq!(
format!("{:?}", Bar { bar: 10, hidden: 1.0 }),
"Bar { bar: 10, .. }",
);
```
Rollup of 5 pull requests
Successful merges:
- #68033 (Don't use f64 shims for f32 cmath functions on non 32-bit x86 MSVC)
- #68244 (Enable leak sanitizer test case)
- #68255 (Remove unused auxiliary file that was replaced with rust_test_helpers)
- #68263 (rustdoc: HTML escape codeblocks which fail syntax highlighting)
- #68274 (remove dead code)
Failed merges:
r? @ghost
When a type error involves a `dyn Trait` as the return type, do not emit
the type error, as the "return type is not `Sized`" error will provide
enough information to the user.
remove dead code
The condition
`if obligation.recursion_depth >= 0`
is always true since `recursion_depth` is `usize`.
The else branch is dead code and can be removed.
Found by Clippy.
Fixes#68251
Enable leak sanitizer test case
* Use `black_box` to avoid memory leak removal during optimization.
* Leak multiple objects to make test case more robust.
Don't use f64 shims for f32 cmath functions on non 32-bit x86 MSVC
These shims are only needed on 32-bit x86. Additionally since https://reviews.llvm.org/rL268875 LLVM handles adding the shims itself for the intrinsics.
The condition
if obligation.recursion_depth >= 0
is always true since recursion_depth is usize.
The else branch is dead code and can be removed.
Found by Clippy.
Fixes#68251
Rollup of 5 pull requests
Successful merges:
- #67780 (Move some queries from rustc::ty to librustc_ty.)
- #68096 (Clean up some diagnostics by making them more consistent)
- #68223 (Use 3.6 instead of 3.5 in float fract() documentation)
- #68265 (Fix some issue numbers of unstable features)
- #68266 (Changed docs for f32 and f64.)
Failed merges:
- #68204 (Use named fields for `{ast,hir}::ItemKind::Impl`)
r? @ghost
Use 3.6 instead of 3.5 in float fract() documentation
It is not self-explanatory whether the fract() function inverts the fractional part of negative numbers. This change clarifies this possible question (so that it is `.6` not `.4`)
Clean up some diagnostics by making them more consistent
In general:
- Diagnostic should start with a lowercase letter.
- Diagnostics should not end with a full stop.
- Ellipses contain three dots.
- Backticks should encode Rust code.
I also reworded a couple of messages to make them read more clearly.
It might be sensible to create a style guide for diagnostics, so these informal conventions are written down somewhere, after which we could audit the existing diagnostics.
r? @Centril
Use pointer offset instead of deref for A/Rc::into_raw
Internals thread: https://internals.rust-lang.org/t/rc-and-internal-mutability/11463/2?u=cad97
The current implementation of (`A`)`Rc::into_raw` uses the `Deref::deref` implementation to get the pointer-to-data that is returned. This is problematic in the proposed Stacked Borrow rules, as this only gets shared provenance over the data location. (Note that the strong/weak counts are `UnsafeCell` (`Cell`/`Atomic`) so shared provenance can still mutate them, but the data itself is not.) When promoted back to a real reference counted pointer, the restored pointer can be used for mutation through `::get_mut` (if it is the only surviving reference). However, this mutates through a pointer ultimately derived from a `&T` borrow, violating the Stacked Borrow rules.
There are three known potential solutions to this issue:
- Stacked Borrows is wrong, liballoc is correct.
- Fully admit (`A`)`Rc` as an "internal mutability" type and store the data payload in an `UnsafeCell` like the strong/weak counts are. (Note: this is not needed generally since the `RcBox`/`ArcInner` is stored behind a shared `NonNull` which maintains shared write provenance as a raw pointer.)
- Adjust `into_raw` to do direct manipulation of the pointer (like `from_raw`) so that it maintains write provenance and doesn't derive the pointer from a reference.
This PR implements the third option, as recommended by @RalfJung.
Potential future work: provide `as_raw` and `clone_raw` associated functions to allow the [`&T` -> (`A`)`Rc<T>` pattern](https://internals.rust-lang.org/t/rc-and-internal-mutability/11463/2?u=cad97) to be used soundly without creating (`A`)`Rc` from references.
