See e3fdc37049: in C++ we generate
explicitly the code for the default action instead of simply copying
blindly the semantic value buffer. This is important when copying
raw memory is not enough, as exemplified by move-only types.
This is currently tested by examples/c++/variant.yy and variant-11.yy.
But it is safer to also have a test in the main test suite.
* tests/local.at (AT_REQUIRE_CXX_STD): Fix.
(AT_BISON_OPTION_PUSHDEFS, AT_BISON_OPTION_POPDEFS): Define/undefine
AT_BISON_OPTIONS.
* tests/c++.at (Default action): New.
d84b245c63