Fortify handing of where bounds on trait & trait alias definitions
Closes https://github.com/rust-lang/rust/issues/96664
Closes https://github.com/rust-lang/rust/issues/96665
Since https://github.com/rust-lang/rust/pull/93803, when listing all bounds and predicates we now need to account for the possible presence of predicates on any of the generic parameters. Both bugs were hidden by the special handling of bounds at the generic parameter declaration position.
Trait alias expansion used to confuse predicates on `Self` and where predicates.
Exiting too late when listing all the bounds caused a cycle error.
Some subst cleanup
Two separate things here. Both changes are useful for some refactoring I'm doing to add an "EarlyBinder" newtype. (Part of chalkification).
1) Remove `subst_spanned` and just use `subst`. It wasn't used much anyways. In practice, I think we can probably get most of the info just from the actual error message. If not, outputting logs should do the trick. (The specific line probably wouldn't help much anyways).
2) Call `.subst()` before `replace_bound_vars_with_fresh_vars` and `erase_late_bound_regions` in three places that do the opposite. I think there might have been some time in the past that the order here matter for something, but this shouldn't be the case anymore. Conceptually, it makes more sense to the of the *early bound* vars on `fn`s as "outside" the late bound vars.
diagnostics: port more diagnostics to derive + add support for `Vec` fields
- Port "unconstrained opaque type" diagnostic to using the derive.
- Allow `Vec` fields in diagnostic derive - enables support for diagnostics that have multiple primary spans, or have subdiagnostics repeated at multiple locations. `Vec<..>` fields in the diagnostic derive become loops in the generated code.
- Add `create_{err,warning}` - there wasn't a way to create a diagnostic from a struct and not emit it straight away.
- Port "explicit generic args w/ impl trait" diagnostic to using the derive.
r? `````@oli-obk`````
cc `````@pvdrz`````
Begin fixing all the broken doctests in `compiler/`
Begins to fix#95994.
All of them pass now but 24 of them I've marked with `ignore HELP (<explanation>)` (asking for help) as I'm unsure how to get them to work / if we should leave them as they are.
There are also a few that I marked `ignore` that could maybe be made to work but seem less important.
Each `ignore` has a rough "reason" for ignoring after it parentheses, with
- `(pseudo-rust)` meaning "mostly rust-like but contains foreign syntax"
- `(illustrative)` a somewhat catchall for either a fragment of rust that doesn't stand on its own (like a lone type), or abbreviated rust with ellipses and undeclared types that would get too cluttered if made compile-worthy.
- `(not-rust)` stuff that isn't rust but benefits from the syntax highlighting, like MIR.
- `(internal)` uses `rustc_*` code which would be difficult to make work with the testing setup.
Those reason notes are a bit inconsistently applied and messy though. If that's important I can go through them again and try a more principled approach. When I run `rg '```ignore \(' .` on the repo, there look to be lots of different conventions other people have used for this sort of thing. I could try unifying them all if that would be helpful.
I'm not sure if there was a better existing way to do this but I wrote my own script to help me run all the doctests and wade through the output. If that would be useful to anyone else, I put it here: https://github.com/Elliot-Roberts/rust_doctest_fixing_tool
Rollup of 8 pull requests
Successful merges:
- #96660 ([bootstrap] Give a better error when trying to run a path with no registered step)
- #96701 (update `jemallocator` example to use 2018 edition import syntax)
- #96746 (Fix an ICE on #96738)
- #96758 (bootstrap: bsd platform flags for split debuginfo)
- #96778 (Remove closures on `expect_local` to apply `#[track_caller]`)
- #96781 (Fix an incorrect link in The Unstable Book)
- #96783 (Link to correct issue in issue-95034 known-bug)
- #96801 (Add regression test for #96319)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Put the incompatible_closure_captures lint messages in alphabetical order
Looks like they were in hash order before, which was causing me trouble in #94598, so this PR sorts the errors by trait name.
Report that opaque types are not allowed in impls even in the presence of other errors
fixes #96569
before this PR those useful errors were hidden because either `unused parameter` or `only traits defined in the current crate can be implemented for arbitrary types` got emitted first.
