https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61689
--- Comment #2 from wmichaelv at hotmail dot com --- (In reply to Marek Polacek from comment #1) > The program has undefined behaviour; an assignment is not a sequence point. > See what -Wsequence-point says. According to the order operation, grouping should be calculated first before add, subtract, division, and multiplication, and assignment. And the associativity of assignment is from right to left.