Auto merge of #127403 - compiler-errors:rollup-x2yb5t0, r=compiler-errors

Rollup of 8 pull requests

Successful merges:

 - #123600 (impl PathBuf::add_extension and Path::with_added_extension)
 - #127107 (Improve dead code analysis)
 - #127221 (Improve well known value check-cfg diagnostic for the standard library)
 - #127333 (Split `SolverDelegate` back out from `InferCtxtLike`)
 - #127363 (Improve readability of some fmt code examples)
 - #127366 (Use `ControlFlow` results for visitors that are only looking for a single value)
 - #127368 (Added dots at the sentence ends of rustc AST doc)
 - #127393 (Remove clubby789 from review rotation)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

crates/salsa/salsa-macros/src/database_storage.rs

@@ -241,11 +241,3 @@ impl Parse for QueryGroup {
         Ok(QueryGroup { group_path })
     }
 }
-
-struct Nothing;
-
-impl Parse for Nothing {
-    fn parse(_input: ParseStream<'_>) -> syn::Result<Self> {
-        Ok(Nothing)
-    }
-}