---

yaml
---
r: 349436
b: refs/heads/master-next
c: ee7ccfd
h: refs/heads/master

Author: swift-ci

[refs]

@@ -1,6 +1,6 @@
 ---
 refs/heads/master: 3574c513bbc5578dd9346b4ea9ab5995c5927bb5
-refs/heads/master-next: 1e5908b47bf540664e07b867aa8b002fee439576
+refs/heads/master-next: ee7ccfd9f3385000c8aae727e2f8c4d15fc3de61
 refs/tags/osx-passed: b6b74147ef8a386f532cf9357a1bde006e552c54
 refs/tags/swift-2.2-SNAPSHOT-2015-12-01-a: 6bb18e013c2284f2b45f5f84f2df2887dc0f7dea
 refs/tags/swift-2.2-SNAPSHOT-2015-12-01-b: 66d897bfcf64a82cb9a87f5e663d889189d06d07

branches/master-next/lib/Sema/TypeCheckDecl.cpp

@@ -3413,8 +3413,10 @@ IsImplicitlyUnwrappedOptionalRequest::evaluate(Evaluator &evaluator,
       }
 
       // If the parameter is not the 'newValue' parameter to a setter, it
-      // must be a subscript index parameter.
-      auto *subscript = cast<SubscriptDecl>(storage);
+      // must be a subscript index parameter (or we have an invalid AST).
+      auto *subscript = dyn_cast<SubscriptDecl>(storage);
+      if (!subscript)
+        return false;
       auto *subscriptParams = subscript->getIndices();
 
       auto where = llvm::find_if(*accessorParams,