[Bug c/63645] Incorrect code generation

[terra at gnome dot org]

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

--- Comment #22 from M Welinder <terra at gnome dot org> ---
>Given
>
>  GnmExprBinary res;
>  GnmExpr const *expr = (GnmExpr *)&res;
>
>the C standard does not define where the result of the conversion points; 

How do you read C99's Section 6.5 #7, then?

Doesn't that tell me I can access my GnmExprBinary via an lvalue that
has a union type that includes a GnmExprBinary member.  GnmExpr is
such a union type.

Specifically, I read the section as allowing use of the lvalue *expr
to access (*expr).binary