common/fmt_common: add has_formatter concept

Signed-off-by: Samuel Just <sjust@redhat.com>

diff --git a/src/common/fmt_common.h b/src/common/fmt_common.h
index 5db8bac43cd7bbd4e5cbc45a81758cefb9e4a6cd..1a2a6eac93576f89234cab81f323904d0c19c7f9 100644 (file)
--- a/src/common/fmt_common.h
+++ b/src/common/fmt_common.h
@@ -15,6 +15,10 @@
  * has a begin()/end() method pair. This is a problem because we have
  * such classes in Crimson.
  */
+
+template <typename T>
+concept has_formatter = fmt::has_formatter<T, fmt::format_context>::value;
+
 /**
  * Tagging classes that provide support for default fmtlib formatting,
  * by having either