[Bug c++/79167] assignment operator LHS side-effect sequenced before RHS computation

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79167

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
N.B. https://gcc.gnu.org/projects/cxx-status.html shows that the "Refining
Expression Evaluation Order for Idiomatic C++" feature (which changed these
rules) isn't supported until GCC 7.