#2397: disable gcc-10 stringop-overflow warning for fmt code

Author: cz4rs

lib/fmt/include/fmt-vt/base.h

@@ -2031,7 +2031,12 @@ FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
 template <typename T, typename InputIt, typename OutputIt,
           FMT_ENABLE_IF(!is_back_insert_iterator<OutputIt>::value)>
 FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
   while (begin != end) *out++ = static_cast<T>(*begin++);
+#pragma GCC diagnostic pop
+#endif
   return out;
 }