Incorrect for loop decompilation

CFR version

a913e06

Compiler

JDK 14, or what ever special compiler IntelliJ uses

Description

The code doesn’t produce the same result after decompilation:

 public static void main(String[] args) {
    int n = 15;
    for (float i = 0; i < n; i++, i*= 2, System.out.println(i), i -= 2, i *= 1.2, i += 0.5) {
    }
  }

prints

2.0
3.0
5.4
11.16
24.984

Decompiled code:

    public static void main(String[] args) {
        int n = 15;
        for (float i = 0.0f; i < (float)n; i -= 2.0f) {
            i += 1.0f;
            System.out.println(i *= 2.0f);
            i = (float)((double)i * 1.2);
            i = (float)((double)i + 0.5);
        }
    }

prints

2.0
3.8000002
8.120001
18.488003

Edit: Not an IDE bug

[leibnitz27]

Yes, it’s a decompiler issue. I can’t speak for the others, as CFR shares 0 heritage with them, but what’s happening for me is that the accounting on the -2 mutation is wrong, at a guess.

Good spot.

[leibnitz27]

It’s the difference between the * and the - looking like (due to the double casts) they can be treated as mutations or not that does it. (slightly different accounting paths.)

Fun one, will try to get to that soonish.