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-rw-r--r--boost/type_erasure/placeholder.hpp5
1 files changed, 4 insertions, 1 deletions
diff --git a/boost/type_erasure/placeholder.hpp b/boost/type_erasure/placeholder.hpp
index 0ea7ab5bce..1311f03bae 100644
--- a/boost/type_erasure/placeholder.hpp
+++ b/boost/type_erasure/placeholder.hpp
@@ -45,7 +45,10 @@ namespace type_erasure {
* explicitly, but the substitution still works the
* same way.
*/
-struct placeholder {};
+struct placeholder {
+ /// INTERNAL ONLY
+ typedef void _boost_type_erasure_is_placeholder;
+};
struct _a : placeholder {};
struct _b : placeholder {};