error[E0384]: cannot assign twice to immutable variable `v`
  --> $DIR/liveness-assign-imm-local-in-op-eq.rs:10:5
   |
LL |     let v: isize;
   |         - help: make this binding mutable: `mut v`
...
LL |     v = 2;  //[ast]~ NOTE first assignment
   |     ----- first assignment to `v`
LL |             //[mir]~^ NOTE first assignment
LL |     v += 1; //[ast]~ ERROR cannot assign twice to immutable variable
   |     ^^^^^^ cannot assign twice to immutable variable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0384`.