remove unnecessary loop

Author: lcnr

Diff for: compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs

@@ -371,14 +371,8 @@ impl RpitConstraintChecker<'_> {
         // Use borrowck to get the type with unerased regions.
         let concrete_opaque_types = &self.tcx.mir_borrowck(def_id).concrete_opaque_types;
         debug!(?concrete_opaque_types);
-        for (&def_id, &concrete_type) in concrete_opaque_types {
-            if def_id != self.def_id {
-                // Ignore constraints for other opaque types.
-                continue;
-            }
-
+        if let Some(&concrete_type) = concrete_opaque_types.get(&self.def_id) {
             debug!(?concrete_type, "found constraint");
-
             if concrete_type.ty != self.found.ty {
                 if let Ok(d) = self.found.build_mismatch_error(&concrete_type, self.tcx) {
                     d.emit();