Auto merge of #13149 - jusexton:issue-13123, r=dswij

Fix while_let_on_iterator dropping loop label when applying fix.

Loop label was not persisted when displaying help and was therefore producing broken rust code when applying fixes.

Solution was to store the `ast::Label` when creating a `higher::WhileLet` from an expression and add the label name to the lint suggestion and diagnostics.

---

Fixes: https://github.com/rust-lang/rust-clippy/issues/13123

changelog: [`while_let_on_iterator`]: Fix issue dropping loop label when displaying help and applying fixes.

clippy_utils/src/higher.rs

@@ -367,6 +367,7 @@ pub struct WhileLet<'hir> {
     pub let_expr: &'hir Expr<'hir>,
     /// `while let` loop body
     pub if_then: &'hir Expr<'hir>,
+    pub label: Option<ast::Label>,
     /// `while let PAT = EXPR`
     ///        ^^^^^^^^^^^^^^
     pub let_span: Span,
@@ -399,7 +400,7 @@ impl<'hir> WhileLet<'hir> {
                     }),
                 ..
             },
-            _,
+            label,
             LoopSource::While,
             _,
         ) = expr.kind
@@ -408,6 +409,7 @@ impl<'hir> WhileLet<'hir> {
                 let_pat,
                 let_expr,
                 if_then,
+                label,
                 let_span,
             });
         }