https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56665
Nikita Kniazev <nok.raven at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |nok.raven at gmail dot com --- Comment #6 from Nikita Kniazev <nok.raven at gmail dot com> --- This is not a GCC bug. The examples above have use after scope bug. Look at `assign_a` documentation https://www.boost.org/doc/libs/1_69_0/libs/spirit/classic/doc/predefined_actors.html it takes a value by reference (by const reference actually).