[fsckboy]

>Since any use of the variable is undefined behavior

use of the variable as an lvalue is not undefined

[kazinator]

When I say that a variable is used, I mean that its value is accessed. This is in line with compiler jargon. In this basic block, the variable x has no next use at the first line; the assignment of 42 is a dead assignment.

  x = 42
  y = w
  x = 43

Search the web for "next-use information".