[Bug c++/83533] error: no type named 'X' in 'using = ...'

[povelikin.rostislav at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83533

--- Comment #1 from Rostislav Povelikin <povelikin.rostislav at gmail dot com> 
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If I change aliasing of u with typedef instead of using - works fine.