Add the option to run UI tests with the parallel frontend
This PR adds two arguments for tests:
1. `--parallel-frontend-threads`: specify `-Zthread` to compile test case (currently UI tests only)
2. `--iteration-count`: the number of times to run each test
Also, due to the non-deterministic diagnostic orders and cycle errors, this PR adds the directive `//@ ignore-parallel-frontend` to ignore tests with cycle error when the parallel-frontend is enabled (by `--parallel-frontend-threads`) and enables `//@ compare-output-by-lines` by default.
Context: [#t-compiler/parallel-rustc > Add the parallel front-end test suite @ 💬](https://rust-lang.zulipchat.com/#narrow/channel/187679-t-compiler.2Fparallel-rustc/topic/Add.20the.20parallel.20front-end.20test.20suite/near/578781369)
This PR should work with https://github.com/rust-lang/rust/pull/153797 together.
Don't look for non-type-level assoc consts when checking trait object types
On main, when looking for assoc items that weren't specified in a given trait object type (via binding), we comb through all (eligible) assoc consts whether type-level or not even though you're not allowed to bind non-type-level assoc consts.
That's usually fine because traits containing (eligible) non-type-level assoc consts are dyn incompatible, so the trait object type is ~already considered ill-formed. Therefore, in PR rust-lang/rust#150843, I saved myself the extra effort, esp. since back then it was more annoying to check if the const item was declared type-level.
<sub>(More concretely: In bodies, we check for all dyn compatibility violations when lowering the trait object type, so we will bail out early with an error; in contrast, item signatures / non-bodies get wfchecked (`WellFormed` obligation) after lowering which includes dyn compatiblity checking (`DynCompatible` obligation); however to reduce the amount of diags, during lowering if there are any unspecified assoc items, we'll check them for dyn compatibility and bail out early if any of them tests negative.)</sub>
Now, we obviously don't wfcheck the defsite of (eager) type aliases which breaks the assumption that such trait object types get rejected. This led to the regression found in rust-lang/rust#153731: The ill-formed trait object type doesn't get rejected (as is expected) but we now require the single (non-type-level) assoc const to be bound in the dyn-Trait which we didn't do before. The actual error talks about dyn incompatibility due to the aforementioned extra check that's usually there to contain the number of diags.
Fixes [after beta backport] rust-lang/rust#153731.
- On `const` and `static` point at the type (like we do for let bindings)
- On fn calls, point at const parameter in fn definition
- On type, point at const parameter in type definition
- On array type lengths, explain that array length is always `usize`
- On enum variant discriminant, mention `repr`
```
error[E0277]: the trait bound `[[u16; 3]; 2]: Bar` is not satisfied
--> $DIR/issue-67185-2.rs:21:6
|
LL | impl Foo for FooImpl {}
| ^^^ the trait `Bar` is not implemented for `[[u16; 3]; 2]`
|
help: the following other types implement trait `Bar`
--> $DIR/issue-67185-2.rs:9:1
|
LL | impl Bar for [u16; 4] {}
| ^^^^^^^^^^^^^^^^^^^^^ `[u16; 4]`
LL | impl Bar for [[u16; 3]; 3] {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ `[[u16; 3]; 3]`
note: required by a bound in `Foo`
--> $DIR/issue-67185-2.rs:14:30
|
LL | trait Foo
| --- required by a bound in this trait
LL | where
LL | [<u8 as Baz>::Quaks; 2]: Bar,
| ^^^ required by this bound in `Foo`
```
When encountering an unmet trait bound, point at local type that doesn't implement the trait:
```
error[E0277]: the trait bound `Bar<T>: Foo` is not satisfied
--> $DIR/issue-64855.rs:9:19
|
LL | pub struct Bar<T>(<Self as Foo>::Type) where Self: ;
| ^^^^^^^^^^^^^^^^^^^ unsatisfied trait bound
|
help: the trait `Foo` is not implemented for `Bar<T>`
--> $DIR/issue-64855.rs:9:1
|
LL | pub struct Bar<T>(<Self as Foo>::Type) where Self: ;
| ^^^^^^^^^^^^^^^^^
```
The suboptimal error only appears with NLLs due to liveness differences
where polonius cannot have as many boring locals. Sometimes this causes
NLLs to emit a duplicate error as well.
```
error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
--> $DIR/attempted-access-non-fatal.rs:7:15
|
LL | let _ = 2.l;
| ^
|
help: if intended to be a floating point literal, consider adding a `0` after the period and a `f64` suffix
|
LL - let _ = 2.l;
LL + let _ = 2.0f64;
|
```
Manually walk into WF obligations in `BestObligation` proof tree visitor
When we encounter a `WellFormed` obligation in the `BestObligation` proof tree visitor, ignore the proof tree and call `wf::unnormalized_obligations` to derive well-formed obligations with the correct cause codes. This is to avoid having to replicate the somewhat delicate logic that `wf.rs` does to set up its obligation causes... Don't see a better way to do this.
vibes?? r? lcnr
Compiler: Finalize dyn compatibility renaming
Update the Reference link to use the new URL fragment from https://github.com/rust-lang/reference/pull/1666 (this change has finally hit stable). Fixes a FIXME.
Follow-up to #130826.
Part of #130852.
~~Blocking it on #133372.~~ (merged)
r? ghost
Don't pick `T: FnPtr` nested goals as the leaf goal in diagnostics for new solver
r? `@lcnr`
See `tests/ui/traits/next-solver/diagnostics/dont-pick-fnptr-bound-as-leaf.rs` for a minimized example of what code this affects the diagnostics off. The output of running nightly `-Znext-solver` on that test is the following:
```
error[E0277]: the trait bound `Foo: Trait` is not satisfied
--> src/lib.rs:14:20
|
14 | requires_trait(Foo);
| -------------- ^^^ the trait `FnPtr` is not implemented for `Foo`
| |
| required by a bound introduced by this call
|
note: required for `Foo` to implement `Trait`
--> src/lib.rs:7:16
|
7 | impl<T: FnPtr> Trait for T {}
| ----- ^^^^^ ^
| |
| unsatisfied trait bound introduced here
note: required by a bound in `requires_trait`
--> src/lib.rs:11:22
|
11 | fn requires_trait<T: Trait>(_: T) {}
| ^^^^^ required by this bound in `requires_trait`
```
Part of rust-lang/trait-system-refactor-initiative#148
This CL makes a number of small changes to dyn compatibility errors:
- "object safety" has been renamed to "dyn-compatibility" throughout
- "Convert to enum" suggestions are no longer generated when there
exists a type-generic impl of the trait or an impl for `dyn OtherTrait`
- Several error messages are reorganized for user readability
Additionally, the dyn compatibility error creation code has been
split out into functions.
cc #132713
cc #133267
Jonathan Brouwer