…2_fix, r=cjgillot

unused-lifetimes: don't warn about lifetimes originating from expanded code

previously, we would warn like this:

````
warning: lifetime parameter `'s` never used
 --> /tmp/unusedlif/code.rs:6:62
  |
5 | #[derive(Clone)]
  |          - help: elide the unused lifetime
6 | struct ShimMethod4<T: Trait2 + 'static>(pub &'static dyn for<'s> Fn(&'s mut T::As));
  |                                                              ^^
  |
  = note: requested on the command line with `-W unused-lifetimes`
````

Fixes rust-lang#104432

…de, r=GuillaumeGomez

rustdoc: use the same URL escape rules for fragments as for examples

Carries over improvements from rust-lang#107284

test: snapshot for derive suggestion in diff files

fixed rust-lang#107649

…eaks, r=lcnr

Implement some tweaks in the new solver

I've been testing the new solver on some small codebases, and these are a few small changes I've needed to make.

The most "controversial" here is implementing `trait_candidate_should_be_dropped_in_favor_of`, which I just implemented to always return false. This surprisingly allows some code to compile, without us having to actually decide on any semantics yet.

r? `@rust-lang/initiative-trait-system-refactor`

…pertraits_into_scope, r=compiler-errors

Do not bring trait alias supertraits into scope

Fixes rust-lang#107747
cc rust-lang#41517

…-if-impl, r=lcnr

Disqualify `auto trait` built-in impl in new solver if explicit `impl` exists