Regression: Code folding regions not detected in R and Python

[jmcphers]

To reproduce, add some code to a Python file that should be foldable, such as a function definition:

def add_to_path(path):
    import sys

    if path not in sys.path:
        sys.path.insert(0, path)

Attempt to fold the code, either with the keyboard shortcuts (https://code.visualstudio.com/docs/editor/codebasics#_folding) or by hovering over the gutter.

No folding regions are detected, and the code can't be folded. R is similarly affected.

Notes:

• Code folding is not universally broken; it works in R and Python if you switch to the less-fancy indentation based folding rules (Editor > Folding Strategy).
• Code folding works using smart features in languages other than R and Python, such as CSS, so this is probably specific to those languages.

Positron Version: 2023.11.0 (Universal) build 1368
Code - OSS Version: 1.84.0
Commit: a71651045484b08ca3f708978761ff1f1072cbc9
Date: 2023-11-29T03:16:22.990Z
Electron: 25.9.2
ElectronBuildId: undefined
Chromium: 114.0.5735.289
Node.js: 18.15.0
V8: 11.4.183.29-electron.0
OS: Darwin arm64 23.1.0

[jmcphers]

Reported by a beta user here: https://github.com/posit-dev/positron-beta/discussions/42

[jmcphers]

Oh, here's the problem:

positron/extensions/positron-code-cells/src/extension.ts

Line 23 in b6ce50f

vscode.languages.registerFoldingRangeProvider('*', new CellFoldingRangeProvider()),

The Positron Code Cells extension is registering itself as the folding provider for everything (including R and Python). That means that when it finds no folding ranges in R or Python files, the editor doesn't draw any folding ranges.

Removing the registration on that line fixes the bug.

VS Code is able to blend folding ranges from multiple providers, but in this case what we really want to do is blend the folding range provider's results with the built-in indentation-based folding range provider. As far as I can tell that is not possible with the existing infrastructure.

[juliasilge]

In Positron 2024.04.0 (Universal) build 1576, we now have our code folding back:

code-folding.mov

I can also confirm code folding works for Python. ✅