Respect rustfmt indentation settings

[0x7CFE]

The code in the if let block was indented by tabs, but "replace with match" suggestion mistakenly indents match arms with spaces.

[matklad]

Yeah, we unfortunately hard-code four space indentation for now.

[Keavon]

This also happens for "Fill match arms".

[0x7CFE]

Out of curiosity, can https://github.com/udoprog/genco be used to generate the code on behalf of RA? It is reportedly whitespace aware and configurable.

[Timmmm]

This is kind of infuriating. What is involved in fixing it? Can I just make the 4 configurable here and here and add some kind of flag to tell it to use tabs instead?

[matklad]

Can I just make the 4 configurable here and here and add some kind of flag to tell it to use tabs instead?

Probably not, editing code should be agnostic about indentation configuration. I think the proper way to fix this is to remove manual indentation entirely in favor of generic indenter: #4182

[flodiebold]

Just as a note, the fact that this is marked unactionable doesn't mean we don't want to fix it, or that no-one is allowed to work on it. It just means we don't see a direct way of making progress on it, because it depends on another issue.

If you care about this and think there is a more simple fix for this, feel free to implement it and make a PR. It just needs to work and be maintainable; it should not make it harder to write assists.

[tehsunnliu]

Hi, any hint where this is hardcoded? and what is causing the problem?

[bjorn3]

Every snippet literally contains the precise amount of spaces to insert. Changing the indentation currently requires updating all snippets AFAIK. Fixing this issue will require some way to either replace the fixed indentation of the snippets or be able to write the snippets without fixed indentation I think.

[WilliamVenner]

hard_tabs and tab_spaces could be read from rustfmt.toml