[Request] Character positions to improve fold text

[Colengms]

This is similar to #50840 , but does not require supporting multiple folding ranges within the same line. Rather, this request is to accept character positions referring to the first and last lines of existing line-granular folding ranges, used only for the purpose of composing the fold text.

Our provider folds blocks down to a single line. For example:

if (b)
{
}

if (b) {
}

do {
    int i;
} while (b);

{
}

Currently fold down to:

if (b)...

if (b) {...

do {...

{...

Note that some syntax can lead to omitting code that wasn't intended to be folded, or showing unmatched braces.

We also have an issue due to the fact that a range may start or end in the middle of a line. For example:

    if (b) { int i;
    } else {
    }

    {
    int j; } int k;

Folds into:

if (b) { int i;...
}

{...

Suggestion: accept start and end character positions for the folded range, and use them to infer the appropriate text to display before and after the fold. For example:

if (b) { int i;
    int i;
int k; } // comment

For the above, we would provide a range of lines 0-2 (all of it), but would indicate start position 8 and end position 7. VS Code could use this info, and existing colorization information, to build the fold text:

if (b) {...} // comment

Similarly, it would clean up:

do {
    int i;
int kj; } while (b);

Such that it's displayed as:

do {...} while (b);

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• [folding] Fold All in selection (#74360)

[aeschli]

We currently have no plans for inline foldings. It would require some major work on the editor widget side.
Duplicate of #50840