[Bug libstdc++/81480] Assertion `ec' failed

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81480

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
You're missing extra flags to set up the necessary include paths.

Why not just run 'make check' instead?