Rollup merge of #101100 - compiler-errors:generalize-call-suggestions, r=petrochenkov

Make call suggestions more general and more accurate

Cleans up some suggestions that have to do with adding `()` to make typeck happy.

1. Drive-by rename of `expr_t` to `base_ty` since it's the type of the `base_expr`
1. Autoderef until we get to a callable type in `suggest_fn_call`.
1. Don't erroneously suggest calling constructor when a method/field does not exist on it.
1. Suggest calling a method receiver if its function output has a method (e.g. `fn.method()` => `fn().method()`)
1. Extend call suggestions to type parameters, fn pointers, trait objects where possible
1. Suggest calling in operators too (fixes #101054)
1. Use `/* {ty} */` as argument placeholder instead of just `_`, which is confusing and makes suggestions look less like `if let` syntax.

1 files changed, 6 insertions, 0 deletions

diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 7660a2f3af6..57555433f55 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -844,6 +844,12 @@ impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Vec<T> {
     }
 }
 
+impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for &[T] {
+    fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+        self.iter().try_for_each(|t| t.visit_with(visitor))
+    }
+}
+
 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         self.try_map_id(|t| t.try_fold_with(folder))