[folding] Incorrect indent level being folded

[Tyriar]

#2994

With this Java file:

package com.growingwiththeweb.sorting;

public class BubbleSort {
    public static void sort(Integer[] array) {
        for (int i = 0; i < array.length - 1; i++) {
            for (int j = 1; j < array.length - i; j++) {
                if (array[j - 1] > array[j]) {
                    swap(array, j, j - 1);
                }
            }
        }
    }

    private static void swap(Integer[] array, int a, int b) {
        Integer temp = array[a];
        array[a] = array[b];
        array[b] = temp;
    }
}

Selecting line number 8 (swap(array, j, j - 1)) and hitting ctrl+shift+[ folds the wrong level:

Adding another if statement within that if again folds 1 level above the correct level.

[tht13]

A further issue here is that if you perform the fold it will not fold, for example:

function foo() {
    bar();
}

However if you add a second line like this:

function foo() {
    bar();
    fux();
}

If you fold/unfold and then remove the new second line and attempt to fold the single line, the folding works. (The same happens with your example above, add a second line in that if statement, fold/unfold it, remove the line, it will then fold correctly.

This is caused by this.decorations returns a two line range for single line collapse regions, so for line 8 (7, zero counting) where you trigger the fold, it will return range: {startLine: 7, endLine: 8} rather than range: {startLine: 7, endLine: 7}.
The added line in the return range then causes the if statement in L374 to fail and in you case it reverts to the surrounding fold range. Or in my example simply does not fold.

I have been unable to debug how these ranges are generated but I am sure @aeschli knows 😄

Hope this helps 👍

[aeschli]

duplicate of #3398

I tested the fix of #3398 with your examples. Thanks @tht13 and @Tyriar !