[libc++] Silences an invalid compiler diagnostic.

When the value is not initialized it's never used. However silencing the
warning is trivial, as suggested by BlamKiwi.

Fixes https://llvm.org/PR63421

diff --git a/libcxx/include/__format/format_arg_store.h b/libcxx/include/__format/format_arg_store.h
index 669b747..afba6c3 100644 (file)
--- a/libcxx/include/__format/format_arg_store.h
+++ b/libcxx/include/__format/format_arg_store.h
@@ -229,7 +229,7 @@ _LIBCPP_HIDE_FROM_ABI void __store_basic_format_arg(basic_format_arg<_Context>*
 template <class _Context, size_t N>
 struct __packed_format_arg_store {
   __basic_format_arg_value<_Context> __values_[N];
-  uint64_t __types_;
+  uint64_t __types_ = 0;
 };
 
 template <class _Context, size_t N>