Add feature gate

compiler/rustc_feature/src/active.rs

@@ -376,6 +376,8 @@ declare_features! (
     (active, deprecated_safe, "1.61.0", Some(94978), None),
     /// Allows having using `suggestion` in the `#[deprecated]` attribute.
     (active, deprecated_suggestion, "1.61.0", Some(94785), None),
+    /// Allows patterns to dereference values to match them.
+    (active, deref_patterns, "1.64.0", Some(87121), None),
     /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.
     (active, doc_auto_cfg, "1.58.0", Some(43781), None),
     /// Allows `#[doc(cfg(...))]`.

compiler/rustc_hir_typeck/src/pat.rs

@@ -401,7 +401,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
         }
 
-        if let hir::ExprKind::Lit(Spanned { node: ast::LitKind::Str(..), .. }) = lt.kind {
+        if self.tcx.features().deref_patterns && let hir::ExprKind::Lit(Spanned { node: ast::LitKind::Str(..), .. }) = lt.kind {
             let tcx = self.tcx;
             let expected = self.resolve_vars_if_possible(expected);
             pat_ty = match expected.kind() {

compiler/rustc_span/src/symbol.rs

@@ -597,6 +597,7 @@ symbols! {
         deref,
         deref_method,
         deref_mut,
+        deref_patterns,
         deref_target,
         derive,
         derive_const,