[libcxx][ios] initialize __fill_val_ in _FillHelper

(cherry picked from commit 6c2bb185d91552032b1140d7c08b43ecf114e066)
llvm · Sep 27, 2024 · ecb50a9 · ecb50a9
1 parent 1a9569c
commit ecb50a9
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/libcxx/include/ios b/libcxx/include/ios
@@ -524,7 +524,10 @@ template <class _Traits>
 // Attribute 'packed' is used to keep the layout compatible with the previous
 // definition of the '__fill_' and '_set_' pair in basic_ios on AIX & z/OS.
 struct _LIBCPP_PACKED _FillHelper {
-  _LIBCPP_HIDE_FROM_ABI void __init() { __set_ = false; }
+  _LIBCPP_HIDE_FROM_ABI void __init() {
+    __set_      = false;
+    __fill_val_ = _Traits::eof();
+  }
   _LIBCPP_HIDE_FROM_ABI _FillHelper& operator=(typename _Traits::int_type __x) {
     __set_      = true;
     __fill_val_ = __x;