[Bug c++/91415] Invalid warning for C++17 sequencing of shift operator E1<<E2.

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91415

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I think this is
P0145R3 Refining Expression Evaluation Order for Idiomatic C++
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0145r3.pdf
which says
4. A SOLUTION
In summary, the following expressions are evaluated in the order a, then b,
then c, then d:
1. a.b
2. a->b
3. a->*b
4. a(b1, b2, b3)
5. b @=a
6. a[b]
7. a << b
8. a >> b