https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69865
--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Bernd Edlinger from comment #1)
> weird:
> If I add -std=c++14 (or any other c++ version, including -ansi)
> to the command line, it works.
As documented in the manual:
-trigraphs
Support ISO C trigraphs. The -ansi option (and -std options for
strict ISO C conformance) implies -trigraphs.
Since the default is -std=gnu++14, -trigraphs is not enabled by default.
