Different behaviors of indent_size and tab_width between editors (Emacs, VSCode)

[kogiokka]

.editorconfig (for example)

root = true

[*]
indent_style = tab
indent_size = 2
tab_width = 5
insert_final_newline = true
trim_trailing_whitespace = true

Indent with/without space

Emacs indents the code with 2 spaces. Wherever the count of spaces meets 5, Emacs replaces it with a tab. On the other hand, VSCode indent the code with 5-space-long tab in the first place.

Emacs

VSCode

Space to Tab exchange rate in code alignment

Set tab_width to 10 in .editorconfig for example.

Emacs replaces 10 spaces with a tab, while VSCode replacing 4 spaces with a tab and display the tab 10 spaces long.

Emacs

VSCode

Expect behavior

A consistent behavior across different editors. Although I'm not sure which implementation is "more correct".

[ffes]

As far as I know vscode itself only has one width for tabs and indenting. So a plugin cannot do much about it.

[10sr]

As for Emacs, this is the expected behavior.

In Emacs, tab_width will be used as a value for tab-width, and indent_size for major-mode specific indentation offset variables.
When tab-width is 4, for example, Emacs converts 4 indentation spaces into one tab if indent-tabs-mode is enabled (which can be turned off by indent_style = space).
Emacs works in this way, and I think it is hard to change this behavior...

But for real cases, IMO, usually it is enough to set indent_size and tab_width to the same value or unset one of them, to avoid thinking about complicated situations like this...

[kogiokka]

The only setting that make these two editor behave the same is indent_size set to tab and tab_width set to 4, which is usually enough. But since the purpose of editorconfig is to maintain consistency between all editors, we need a standard behavior no matter how the settings varies.

So for the case of Emacs and VSCode, either Emacs complies with VSCode or the other way around. For example, implement the Emacs' plugin bottom-top instead of using the built-in tab-width variable, or request VSCode dev team to do a more flexible indent mechanism. And I believe there are more editors have different behaviors with each other out there, Emacs vs VSCode is just one example.

[xuhdev]

Emacs' behavior complies, as this setup is supposed to handle source code where size of indent is smaller than a tab, but a tab is used whenever its defined width can fit in. Examples include gcc and vim, both of which uses a tab of size 8 and indent level of size 4. Per my understanding, VS Code does not comply simply because of its limitation. We can somewhat count this as a bug, but also requires a fix from VSCode side.

[Artoria2e5]

FWIW, the VSCode issue is microsoft/vscode#42740. Or microsoft/vscode#5394.