Autoformat tab size does not change

[tsumanuma]

Describe the problem

Sorry if I'm rude as this is the first time I've used this.

I would like to change the tab size from 2 to 4
I was able to change the width when typing with the keyboard, but not when auto-formatting.

Please, and thank you

To reproduce

In the Command Palette (Ctrl+Shift+P), select "Preferences". Selected "Open Preferences".
I then selected "Editor"; in the Advanced Settings GUI I selected "Tab Size" and changed it.

Expected behavior

When I press Control + T, the tab is formatted with two sizes

Arduino IDE version

2.0.0-rc8

Operating system

Windows

Operating system version

10

Additional context

No response

Issue checklist

• I searched for previous reports in the issue tracker
• I verified the problem still occurs when using the latest nightly build
• My report contains all necessary details

[per1234]

Hi @tsumanuma. Thanks for your report.

As a workaround, I can share the work in progress documentation for customizing the Auto Format configuration according to your preferences:

https://github.com/arduino/docs-content/blob/b43294a6e16e73877e9146ff858c55511e1e0c2a/content/software/ide-v2/tutorials/ide-v2-customize-auto-formatter/content.md

❗ There is currently an error in that document (which will be corrected before it is published on arduino.cc): The file name (custom_configuration.clang-format) shown in the screenshot is invalid. The file must be named .clang-format.

If you would like to change the indent size to 4, copy the configuration provided in the documentation, but change this line:

IndentWidth: 2

to this:

IndentWidth: 4

---

In order to make relevant information available to all interested parties, I'll link to the previous report for Arduino IDE 1.x: arduino/Arduino#5012

[tsumanuma]

It worked!
Thank you so much!

[per1234]

You are welcome.

I'm glad the workaround was helpful. However, I think that we should eventually make the Arduino IDE 2.x work correctly without the need for such a workaround. So I hope you won't mind that I am reopening this issue so that we can effectively track that task.

I have learned more about the IDE's auto formatter and about the ClangFormat tool recently and I now understand several important things:

The IDE adjusts the formatter configuration

Unlike the Arduino IDE 1.x, where the formatter configuration is completely independent from the editor configuration, Arduino IDE 2.x has a sophisticated system for adjusting the formatter configuration according to the user's advanced settings for the editor:

• "Editor: Insert Spaces" (editor.insertSpaces)
• "Editor: Tab Size" (editor.tabSize)

The code is here:

https://github.com/arduino/arduino-ide/blob/main/arduino-ide-extension/src/node/clang-formatter.ts

ClangFormat has a complex way of using tabs

During the formatting process, ClangFormat does the initial indentation using spaces, according to the IndentWidth configuration setting value.

If use of tabs for the final indents is indicated by the UseTab configuration setting, those spaces are then converted to tabs according to the value of TabWidth. For example, if TabWidth is set to 4, then every occurrence of four spaces within the scope of the UseTab setting is converted to a tab.

This means there is a complex interaction between the IndentWidth and TabWidth values, which can produce unexpected results. For example, if IndentWidth is set to 2 and TabWidth to 4, every two indent levels is converted to a single tab, leaving two spaces for the final indentation of each odd level.

The IDE does not correctly adjust the formatter configuration

Due to the way ClangFormat uses tabs, the expected output will only be produced when the IndentWidth and TabWidth ClangFormat configuration settings are set to the same value.

Currently, the IDE adjusts only the TabWidth value according to the user's editor.tabSize editor setting, leaving IndentWidth at the standard value of 2.

So if you have the following IDE configuration:

{
  "editor.insertSpaces": false,
  "editor.tabSize": 4
}

The editor will produce the expected results:

but the IDE's "Auto Format" will produce something very odd:

(the → are tabs and the • are spaces)