Indentation-based approach to folding is not effective

[per1234]

Describe the problem

The IDE's code folding system assumes that code blocks will always be indented, and that indented text is always a code block.

🐛 This not a valid assumption. As a result, some code blocks are not foldable, some don't fold correctly, and some things fold that should not.

To reproduce

1. Open a sketch that contains code with structure not reflected by indentation:

   /*
   this is not foldable
     this is foldable
   */
   
   /* this block is not foldable
   the IDE does not indent the contents of block comments
   */
   
   void setup() {  // this block is not foldable
   #ifdef FOO  // common code style is no indentation preprocessor blocks, since they are independent from the C++ code structure
     // this block is foldable
   #endif
   }
   
   void loop() { // This block folds incorrectly
     // only this line is folded when folding the `loop` block
   #ifdef FOO
     // this block is foldable
   #endif  // this is treated as a block
     // this is not folded when folding the `loop` block
   bar:  // this is treated as a block
     ; // this is not folded when folding the `loop` block
   }

2. Hover the mouse pointer up and down through the left margin of the editor pane in the IDE. Noting the locations of the fold controls.

   • 🐛 Expected fold controls are missing at lines 1, 6, and 10.
   • 🐛 An unexpected fold control is present at lines 2 and 22.

   

3. Do a "Fold All". Note the results.

   • 🐛 Lines 7, 11-13, 18, 20, and 22 are not folded as expected

   

Expected behavior

Folding occurs based on code structure, independent from indentation.

Arduino IDE version

Original report

2.0.0-beta.12-nightly.20211021

Last verified with

63e9dfd

Operating system

Windows

Operating system version

• Windows 10
• Windows 11

Additional context

Previously reported at arduino/arduino-pro-ide#13 and claimed to be fixed at that time, so perhaps a regression.

---

Folding is more reliable in the Arduino IDE 1.x:

Additional reports

• https://forum.arduino.cc/t/some-suggestions-about-edi-v2-beta4/700972
• https://forum.arduino.cc/t/block-folding-stops-at-ifdef/863239
• https://forum.arduino.cc/t/option-to-hide-comments/900318/7
• https://forum.arduino.cc/t/function-folding-glitch-on-latest-2-3-3/1322326

Issue checklist

• I searched for previous requests in the issue tracker
• I verified the feature was still missing when using the latest nightly build
• My request contains all necessary details