I wonder if we want this patch:
--- a/libstdc++-v3/include/std/utility
+++ b/libstdc++-v3/include/std/utility
@@ -74,6 +74,9 @@
#include <type_traits>
#include <bits/move.h>
#include <initializer_list>
+#if __cplusplus == 201703L && defined __STRICT_ANSI__
+# include <charconv>
+#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
In the published C++17 standard, std::to_chars and std::from_chars are
meant to be in <utility>. The new <charconv> header was only
introduced post-C++17 by a defect report (specifically, by P0682R1).
But maybe this isn't needed, because there's no code in the wild that
was written before <charconv> was invented, so everybody should
already be using that.
