Can't compile while loop with i'

[catap]

Compiler version

I can reproduce it on: 3.0.0-M3-bin-20201213-e8d748e-NIGHTLY and 3.0.0-RC1-bin-20210122-6947b0f-NIGHTLY

Minimized code

object HelloWorld {
  def whileLoop: Int = {
    var i = 0
    var acc = 0
    while (i < 3) {
      var `i'` = 0
      while (`i'` < 4) {
        acc += (i * `i'`)
        `i'` += 1
      }
      i += 1
    }
    acc
  }

  def main(args: Array[String]): Unit = {
    println(s"hello world: ${whileLoop}")
  }
}

Output

-- Error: tests/pos/HelloWorld.scala:9:16 --------------------------------------
9 |        `i'` += 1
  |                ^
  |                end of statement expected but integer literal found
-- [E040] Syntax Error: tests/pos/HelloWorld.scala:10:6 ------------------------
10 |      }
   |      ^
   |      ';' expected, but '}' found
-- [E008] Not Found Error: tests/pos/HelloWorld.scala:8:12 ---------------------
8 |        acc += (i * `i'`)
  |        ^^^^^^
  |        value += is not a member of Int - did you mean Int.!=?
-- [E008] Not Found Error: tests/pos/HelloWorld.scala:9:8 ----------------------
8 |        acc += (i * `i'`)
9 |        `i'` += 1
  |               ^
  |              value i' is not a member of Int.
  |              Note that `i'` is treated as an infix operator in Scala 3.
  |              If you do not want that, insert a `;` or empty line in front
  |              or drop any spaces behind the operator.
-- [E006] Not Found Error: tests/pos/HelloWorld.scala:9:13 ---------------------
9 |        `i'` += 1
  |             ^^
  |             Not found: +=

longer explanation available when compiling with `-explain`
5 errors found

Expectation

Should compile and print hello world: 18

Workaround

Replace lines like:

 `i'` += 1

to

 `i'` = `i'` + 1