Rollup of 26 pull requests
Successful merges:
- #56425 (Redo the docs for Vec::set_len)
- #56906 (Issue #56905)
- #57042 (Don't call `FieldPlacement::count` when count is too large)
- #57175 (Stabilize `let` bindings and destructuring in constants and const fn)
- #57192 (Change std::error::Error trait documentation to talk about `source` instead of `cause`)
- #57296 (Fixed the link to the ? operator)
- #57368 (Use CMAKE_{C,CXX}_COMPILER_LAUNCHER for ccache)
- #57400 (Rustdoc: update Source Serif Pro and replace Heuristica italic)
- #57417 (rustdoc: use text-based doctest parsing if a macro is wrapping main)
- #57433 (Add link destination for `read-ownership`)
- #57434 (Remove `CrateNum::Invalid`.)
- #57441 (Supporting backtrace for x86_64-fortanix-unknown-sgx.)
- #57450 (actually take a slice in this example)
- #57459 (Reference tracking issue for inherent associated types in diagnostic)
- #57463 (docs: Fix some 'second-edition' links)
- #57466 (Remove outdated comment)
- #57493 (use structured suggestion when casting a reference)
- #57498 (make note of one more normalization that Paths do)
- #57499 (note that FromStr does not work for borrowed types)
- #57505 (Remove submodule step from README)
- #57510 (Add a profiles section to the manifest)
- #57511 (Fix undefined behavior)
- #57519 (Correct RELEASES.md for 1.32.0)
- #57522 (don't unwrap unexpected tokens in `format!`)
- #57530 (Fixing a typographical error.)
- #57535 (Stabilise irrefutable if-let and while-let patterns)
Failed merges:
r? @ghost
Reference tracking issue for inherent associated types in diagnostic
This makes it clearer that associated types in inherent impls are an intended feature, like the diagnostic for equality constraints in where clauses. (This is more helpful, because the lack of associated types is a confusing omission and it lets users more easily track the state of the feature.)
Stabilize `let` bindings and destructuring in constants and const fn
r? @Centril
This PR stabilizes the following features in constants and `const` functions:
* irrefutable destructuring patterns (e.g. `const fn foo((x, y): (u8, u8)) { ... }`)
* `let` bindings (e.g. `let x = 1;`)
* mutable `let` bindings (e.g. `let mut x = 1;`)
* assignment (e.g. `x = y`) and assignment operator (e.g. `x += y`) expressions, even where the assignment target is a projection (e.g. a struct field or index operation like `x[3] = 42`)
* expression statements (e.g. `3;`)
This PR does explicitly *not* stabilize:
* mutable references (i.e. `&mut T`)
* dereferencing mutable references
* refutable patterns (e.g. `Some(x)`)
* operations on `UnsafeCell` types (as that would need raw pointers and mutable references and such, not because it is explicitly forbidden. We can't explicitly forbid it as such values are OK as long as they aren't mutated.)
* We are not stabilizing `let` bindings in constants that use `&&` and `||` short circuiting operations. These are treated as `&` and `|` inside `const` and `static` items right now. If we stopped treating them as `&` and `|` after stabilizing `let` bindings, we'd break code like `let mut x = false; false && { x = true; false };`. So to use `let` bindings in constants you need to change `&&` and `||` to `&` and `|` respectively.
NLL: Fix bug in associated constant type annotations.
Fixes#57280.
This PR reverses the variance used when relating types from the type
annotation of an associated constant - this matches the behaviour of the
lexical borrow checker and fixes a bug whereby matching a `&'a str`
against a `&'static str` would produce an error.
r? @nikomatsakis
tests: Do not use `-Z parse-only`, continue compilation to test recovery
Make tests closer to reality!
The next step will be enabling `-Z continue-parse-after-error` by default and looking at the regressions.
A few instances of `-Z parse-only` are kept when it's appropriate, see e.g `ui/impl-trait/impl-trait-plus-priority.rs`, which tests mostly semantically wrong code and would generate too much useless noise if allowed to continue.
use structured suggestion for method calls
Furthermore, don't suggest calling the method if it is part of a place
expression, as this is invalid syntax.
I'm thinking it might be worth putting a label on the method assignment span like "this is a method" and removing the span from the "methods are immutable" text so it isn't reported twice.
The suggestions in `src/test/ui/did_you_mean/issue-40396.stderr` are suboptimal. I could check if the containing expression is `BinOp`, but I'm not sure if that's general enough. Any ideas?
r? @estebank
Fix#56806 by using `delay_span_bug` in object safety layout sanity checks
It's possible that `is_object_safe` is called on a trait method that with an invalid receiver type. This caused an ICE in #56806, because `receiver_is_dispatchable` returns `true` for `self: Box<dyn Trait>`, which causes one of the layout sanity checks in object_safety.rs to fail. Replacing `bug!` with `delay_span_bug` solves this.
The fact that `receiver_is_dispatchable` returns `true` here could be considered a bug. It passes the check that the method implements, though: `Box<dyn Trait>` implements `DispatchFromDyn<Box<dyn Trait>>` because `dyn Trait` implements `Unsize<dyn Trait>`. It would be good to hear what @eddyb and @nikomatsakis think.
Note that I only added a test for the case encountered in #56806. I could not come up with a case that triggered an ICE from the other check, `bug!("receiver when Self = dyn Trait should be ScalarPair, found Scalar")`. There is no way, to my knowledge, that you can make `receiver_is_dispatchable` return true but still have a `Scalar` ABI when `Self = dyn Trait`.
One other case I encountered while debugging #56806 was that if you have a type parameter `T` that implements `Deref<Target=Self>` and `DispatchFromDyn<T>`, and use it as a method receiver, it will cause an ICE during `is_object_safe` because `T` has no layout ([playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=d9b7497b3be0ca8382fa7d9497263214)):
```rust
trait Trait<T: Deref<Target=Self> + DispatchFromDyn<T>> {
fn foo(self: T) -> dyn Trait<T>;
}
```
I don't intend to remove the ICE there because it is a pathological case, especially since there is no way to implement `DispatchFromDyn<T>` for `T` — the checks in typeck/coherence/builtin.rs do not allow that.
fixes#56806
r? @varkor
NLL: Add closure cannot be moved note.
Fixes#57098.
This PR extends existing logic for checking whether a closure that
is `FnOnce` and therefore moves variables that it captures from the
environment has already been invoked when being invoked again.
Now, this logic will also check whether the closure is being moved after
previously being moved or invoked and add an appropriate note.
r? @pnkfelix
Add support for trait-objects without a principal
The hard-error version of #56481 - should be merged after we do something about the `traitobject` crate.
Fixes#33140.
Fixes#57057.
r? @nikomatsakis
Implement the Re-rebalance coherence RFC
This is the first time I touch anything in the compiler so just tell me if I got something wrong.
Big thanks to @sgrif for the pointers where to look for those things.
cc #55437
It's possible that `is_object_safe` is called on a trait that is ill-formed, and we shouldn't ICE unless there are no errors being raised. Using `delay_span_bug` solves this.
fixes#56806
make `panictry!` private to libsyntax
This commit completely removes usage of the `panictry!` macro from
outside libsyntax. The macro causes parse errors to be fatal, so using
it in libsyntax_ext caused parse failures *within* a syntax extension to
be fatal, which is probably not intended.
Furthermore, this commit adds spans to diagnostics emitted by empty
extensions if they were missing, à la #56491.
