[CSBindings] Optional object type variable should be connected to the optional

lib/Sema/CSBindings.cpp

@@ -1671,6 +1671,16 @@ PotentialBindings::inferFromRelational(Constraint *constraint) {
       break;
     }
 
+    case ConstraintKind::OptionalObject: {
+      // Type variable that represents an object type of
+      // an un-inferred optional is adjacent to a type
+      // variable that presents such optional (`bindingTypeVar`
+      // in this case).
+      if (kind == AllowedBindingKind::Supertypes)
+        AdjacentVars.insert({bindingTypeVar, constraint});
+      break;
+    }
+
     default:
       break;
     }

lib/Sema/CSSimplify.cpp

@@ -5424,8 +5424,14 @@ bool ConstraintSystem::repairFailures(
       auto contextualTy = simplifyType(rhs)->getOptionalObjectType();
       if (!lhs->getOptionalObjectType() && !lhs->hasTypeVariable() &&
           contextualTy && !contextualTy->isTypeVariableOrMember()) {
-        conversionsOrFixes.push_back(IgnoreContextualType::create(
-            *this, lhs, rhs, getConstraintLocator(OEE->getSubExpr())));
+        auto *fixLocator = getConstraintLocator(OEE->getSubExpr());
+        // If inner expression already has a fix, consider this two-way
+        // mismatch as un-salvageable.
+        if (hasFixFor(fixLocator))
+          return false;
+
+        conversionsOrFixes.push_back(
+              IgnoreContextualType::create(*this, lhs, rhs, fixLocator));
         return true;
       }
     }

test/stmt/foreach.swift

@@ -341,3 +341,13 @@ do {
     }
   }
 }
+
+// https://github.com/apple/swift/issues/73207
+do {
+  func test(_ levels: [Range<Int>]) {
+    for (i, leaves): (Int, Range<Int>) in levels[8 ..< 15].enumerated() { // Ok
+      _ = i
+      _ = leaves
+    }
+  }
+}