Fix compile panic on non existent type return
Reverted the change 28a76a9000 (diff-4ed25c00aceb84666fca639cf8101c7cL1069) which was panicking when returning a type that cannot be found in the current scope and added testing for the compile error.
For example:
```rust
fn addition() -> Wrapper<impl A> {}
```
Where Wrapper is undefined in the scope.
Fix#50865: ICE on impl-trait returning functions reaching private items
Adds a test case as suggested in #50865, and implements @petrochenkov's suggestion. Fixes#50865.
Impl-trait-returning functions are marked under a new (low) access level, which they propagate rather than `AccessLevels::Reachable`. `AccessLevels::is_reachable` returns false for such items (leaving stability analysis unaffected), these items may still be visible to the lints phase however.
Lament the invincibility of the Turbofish
Here a test case is added to ensure that any others attempting to drive the Turbofish to extinction have second thoughts. Previously the [entire test suite would succeed](https://github.com/rust-lang/rust/pull/53511) if generic arguments were accepted without disambiguation, making for [confusing and heartbreaking circumstances](https://github.com/rust-lang/rfcs/pull/2527).
Use optimized SmallVec implementation
This PR replaces current SmallVec implementation with the one from the Servo project.
Closes https://github.com/rust-lang/rust/issues/51640
r? @Mark-Simulacrum
Feature gate where clauses on associated type impls
Fixes#52913. This doesn't address the core problem, which is tracked by https://github.com/rust-lang/rust/issues/47206. However, it fixes the stable-to-stable regression: you now have to enable `#![feature(generic_associated_types)]` to trigger the weird behaviour.
- Original cycle error diagnostics PR'd against this issue caught
panic-causing error while resolving std::mem::transmute calls
- Now, catch invalid use case of not providing a concrete sized type
behind existential type in definining use case.
- Update relevant test to reflect this new error
52985: revert normalize query changes
- PR 53588 invalidates 53316, causing a correct cycle error to occur
with a good span.
- Don't need to revert the whole merge as the test files are
still fine, just need to revert the normalize query changes.
- It should now be correct that infinite recursion detected during
normalize query type folding is a bug, should have been caught earlier
(when resolving the existential type's defining use cases).
52985: code review impl
- Only cause cycle error if anonymous type resolves to anonymous type
that has the same def id (is the same type) as the original (parent)
type.
- Add test case to cover this case for existential types.
52985: remove Ty prefix from TyAnon
- To align with changes per commit 6f637da50c
Allow panicking with string literal messages inside constants
r? @eddyb
cc https://github.com/rust-lang/rust/issues/51999
we can't implement things like `panic!("foo: {}", x)` right now because we can't call trait methods (most notably `Display::fmt`) inside constants. Also most of these impls probably have loops and conditions, so it's messy anyway.
But hey `panic!("foo")` works at least.
cc @japaric got any test ideas for `#![no_std]`?
Rollup of 10 pull requests
Successful merges:
- #53418 (Mark some suggestions as MachineApplicable)
- #53431 (Moved some feature gate ui tests to correct location)
- #53442 (Update version of rls-data used with save-analysis)
- #53504 (Set applicability for more suggestions.)
- #53541 (Fix missing impl trait display as ret type)
- #53544 (Point at the trait argument when using unboxed closure)
- #53558 (Normalize source line and column numbers.)
- #53562 (Lament the invincibility of the Turbofish)
- #53574 (Suggest direct raw-pointer dereference)
- #53585 (Remove super old comment on function that parses items)
Failed merges:
- #53472 (Use FxHash{Map,Set} instead of the default Hash{Map,Set} everywhere in rustc.)
- #53563 (use String::new() instead of String::from(""), "".to_string(), "".to_owned() or "".into())
r? @ghost
Lament the invincibility of the Turbofish
Here a test case is added to ensure that any others attempting to drive the Turbofish to extinction have second thoughts. Previously the [entire test suite would succeed](https://github.com/rust-lang/rust/pull/53511) if generic arguments were accepted without disambiguation, making for [confusing and heartbreaking circumstances](https://github.com/rust-lang/rfcs/pull/2527).
