[Bug c++/81852] Feature request: __cpp_threadsafe_static_init

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81852

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yes. The dg-options directive disables the features, then the dg-error
directives check for the expected #error diagnostics.

This uses DejaGnu to check for the three specific expected results, rather than
just expecting compilation to pass/fail, which would only be a binary result.