Rollup merge of #70821 - rkuhn:expose_suggestions_InferCtxtExt, r=eddyb

expose suggestions::InferCtxtExt for clippy

This is very useful to do good async/await diagnostic reporting, for example for rust-lang/rust-clippy#5423.

Author: Dylan-DPC

src/librustc_trait_selection/traits/error_reporting/suggestions.rs

@@ -22,7 +22,8 @@ use std::fmt;
 use super::InferCtxtPrivExt;
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
 
-crate trait InferCtxtExt<'tcx> {
+// This trait is public to expose the diagnostics methods to clippy.
+pub trait InferCtxtExt<'tcx> {
     fn suggest_restricting_param_bound(
         &self,
         err: &mut DiagnosticBuilder<'_>,