[Bug c/63645] Incorrect code generation

[mikpelinux at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63645

--- Comment #10 from Mikael Pettersson <mikpelinux at gmail dot com> ---
I now think the test case is invalid.  There is special provision in the
standard for accessing "the wrong member" of a union, but the member has to be
a struct type which shares a prefix with the current dynamic member (which also
has to be a struct).  That is, if you wrap the oper member of _GnmExpr in a
struct then I think the program is valid.