HIR debug output is currently very verbose, especially when used with
the alternate (`#`) flag. This commit reduces the amount of noisy
newlines by forcing a few small key types to stay on one line, which
makes the output easier to read and scroll by.
```
$ rustc +after hello_world.rs -Zunpretty=hir-tree | wc -l
582
$ rustc +before hello_world.rs -Zunpretty=hir-tree | wc -l
932
```
refactor: merge error code `E0465` into `E0464`
`E0465` is an undocumented and untested error code that is functionally identical to `E0464`. This PR merges `E0465` into `E0464`, thus documenting and testing another error code (#61137).
r? `@GuillaumeGomez` (not sure if you want to review this but it's relevant to my other PRs that you have reviewed)
Revert "Implement allow-by-default `multiple_supertrait_upcastable` lint"
This is a clean revert of #105484.
I confirmed that reverting that PR fixes the regression reported in #106247. ~~I can't say I understand what this code is doing, but maybe it can be re-landed with a different implementation.~~ **Edit:** https://github.com/rust-lang/rust/issues/106247#issuecomment-1367174384 has an explanation of why #105484 ends up surfacing spurious `where_clause_object_safety` errors. The implementation of `where_clause_object_safety` assumes we only check whether a trait is object safe when somebody actually uses that trait with `dyn`. However the implementation of `multiple_supertrait_upcastable` added in the problematic PR involves checking *every* trait for whether it is object-safe.
FYI `@nbdd0121` `@compiler-errors`
The test was minified from the published `msf-ice:0.2.1` crate which failed in a crater run.
A faulty compiler was triggering a `higher-ranked lifetime error`:
> could not prove `[async block@...]: Send`
Rollup of 9 pull requests
Successful merges:
- #104531 (Provide a better error and a suggestion for `Fn` traits with lifetime params)
- #105899 (`./x doc library --open` opens `std`)
- #106190 (Account for multiple multiline spans with empty padding)
- #106202 (Trim more paths in obligation types)
- #106234 (rustdoc: simplify settings, help, and copy button CSS by not reusing)
- #106236 (docs/test: add docs and a UI test for `E0514` and `E0519`)
- #106259 (Update Clippy)
- #106260 (Fix index out of bounds issues in rustdoc)
- #106263 (Formatter should not try to format non-Rust files)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
docs/test: add docs and a UI test for `E0514` and `E0519`
No UI test on `E0514`, it would need to compile with a different `rustc` version.
r? `@GuillaumeGomez`
Provide a better error and a suggestion for `Fn` traits with lifetime params
Given `Fn`-family traits with lifetime params in trait bounds like `fn f(_: impl Fn<'a>(&'a str) -> bool)`, we currently produce many unhelpful errors.
This PR allows these situations to suggest simply using Higher-Rank Trait Bounds like `for<'a> Fn(&'a str) -> bool`.
Fixes https://github.com/rust-lang/rust/issues/103490.
Make trait/impl `where` clause mismatch on region error a bit more actionable
Improve `where` clause suggestions for GATs/methods that have incompatible region predicates in their `where` clauses.
Also addresses this diagnostic that went away https://github.com/rust-lang/rust/pull/106129#discussion_r1056875772
Improve heuristics whether `format_args` string is a source literal
Previously, it only checked whether there was _a_ literal at the span of the first argument, not whether the literal actually matched up. This caused issues when a proc macro was generating a different literal with the same span.
This requires an annoying special case for literals ending in `\n` because otherwise `println` wouldn't give detailed diagnostics anymore which would be bad.
Fixes#106191
Currently, given `Fn`-family traits with lifetime params like
`Fn<'a>(&'a str) -> bool`, many unhelpful errors show up. These are a
bit confusing.
This commit allows these situations to suggest simply using
higher-ranked trait bounds like `for<'a> Fn(&'a str) -> bool`.
Properly calculate best failure in macro matching
Previously, we used spans. This was not good. Sometimes, the span of the token that failed to match may come from a position later in the file which has been transcribed into a token stream way earlier in the file. If precisely this token fails to match, we think that it was the best match because its span is so high, even though other arms might have gotten further in the token stream.
We now try to properly use the location in the token stream.
This needs a little cleanup as the `best_failure` field is getting out of hand but it should be mostly good to go. I hope I didn't violate too many abstraction boundaries..
Previously, it only checked whether there was _a_ literal at the span of
the first argument, not whether the literal actually matched up. This
caused issues when a proc macro was generating a different literal with
the same span.
This requires an annoying special case for literals ending in `\n`
because otherwise `println` wouldn't give detailed diagnostics anymore
which would be bad.
Some `compare_method` tweaks
1. Make some of the comparison functions' names more regular
2. Reduce pub scope of some of the things in `compare_method`
~3. Remove some unnecessary opaque type handling code -- `InferCtxt` already is in a mode that doesn't define opaque types~
* moved to a different PR
4. Bubble up `ErrorGuaranteed` for region constraint errors in `compare_method` - Improves a redundant error message in one unit test.
5. Move the `compare_method` module to have a more general name, since it's more like `compare_impl_item` :)
6. Rename `collect_trait_impl_trait_tys`
Implement allow-by-default `multiple_supertrait_upcastable` lint
The lint detects when an object-safe trait has multiple supertraits.
Enabled in libcore and liballoc as they are low-level enough that many embedded programs will use them.
r? `@nikomatsakis`
