Allow formatter using 'filepath on a modified buffer

[andersk]

Fixes #109.

[mohkale]

I don't think this is a good idea. The restriction from formatting when the buffer is modified is because it assumes the formatter is formatting the file, not the buffer, and then when we try to apply the changes atop the buffer because it doesn't match what was there before formatting there could be some discrepencies. That said I'm also not a big fan of the current state of this. It might be better to add an option to auto-save the buffer before running the formatter or add a new field (aside from filepath) which indicates to apheleia "yes, this uses the filepath, but it still formats through stdin".

[andersk]

filepath is the option that indicates to apheleia “yes, this uses the filepath, but still formats through stdin”. If you want to avoid indicating that, you use file instead of filepath. See this existing comment:

apheleia/apheleia.el

Lines 959 to 961 in 12804a5

	it. (Use `filepath' instead of `file' if you need the filename of
	the current buffer, but you still want its contents to be passed
	on stdin.)

Also, I consider it very important that formatting a buffer does not save it. For me, formatting is as integral to the editing experience as pressing the space bar, and I would never want an editor that auto-saved every time I pressed the space bar.

[elken]

I can see this argument and I'm kinda in favour of it.

The thought of making the formatting run more transparently during typing is an interesting one.

[raxod502]

You're right. There is no need to block formatting on a modified buffer for filepath, only for file.

[raxod502]

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