[libc++] Allow building with C++17.

After committing D92214 it was noticed libc++ no longer builds with
C++17. For now reenable building with C++17. This is intended to be a
temporary measure in the future a C++20 capable compiler will be
required.

diff --git a/libcxx/src/format.cpp b/libcxx/src/format.cpp
index 8ae9554..c36c20e 100644 (file)
--- a/libcxx/src/format.cpp
+++ b/libcxx/src/format.cpp
@@ -10,6 +10,10 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#if _LIBCPP_STD_VER > 17
+
 format_error::~format_error() noexcept = default;
 
+#endif //_LIBCPP_STD_VER > 17
+
 _LIBCPP_END_NAMESPACE_STD