Auto merge of #11792 - y21:issue11764, r=llogiq

[`map_identity`]: respect match ergonomics

Fixes #11764

Note: the original tests before this were slightly wrong themselves already and had to be changed. They were calling `map` on an iterator of `&(i32, i32)`s, so this PR would stop linting there, but they were meant to test something else unrelated to binding modes, so I just changed them to remove the references so that it iterates over owned values and they all bind by value. This way they continue to test what they checked for before: the identity function for tuple patterns.

changelog: [`map_identity`]: respect match ergonomics

clippy_utils/src/lib.rs

@@ -2023,6 +2023,18 @@ pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
 /// Consider calling [`is_expr_untyped_identity_function`] or [`is_expr_identity_function`] instead.
 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
     fn check_pat(cx: &LateContext<'_>, pat: &Pat<'_>, expr: &Expr<'_>) -> bool {
+        if cx
+            .typeck_results()
+            .pat_binding_modes()
+            .get(pat.hir_id)
+            .is_some_and(|mode| matches!(mode, BindingMode::BindByReference(_)))
+        {
+            // If a tuple `(x, y)` is of type `&(i32, i32)`, then due to match ergonomics,
+            // the inner patterns become references. Don't consider this the identity function
+            // as that changes types.
+            return false;
+        }
+
         match (pat.kind, expr.kind) {
             (PatKind::Binding(_, id, _, _), _) => {
                 path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty()