LSP: Use workspace/willRenameFiles to handle rename resource operations

[the-mikedavis]

With the addition of LSP renaming in #8584 we now declare willRename support - that we will send a workspace/willRenameFiles before renaming a file. The spec says that this should be used for workspace edits as well as user commands (emphasis mine):

The will rename files request is sent from the client to the server before files are actually renamed as long as the rename is triggered from within the client either by a user action or by applying a workspace edit.

Currently we just rename the file when receiving a workspace edit that attempts to rename a file (which was the proper behavior when we didn't declare willRename support):

helix/helix-term/src/commands/lsp.rs

Lines 827 to 837 in b023faa

	ResourceOp::Rename(op) => {
	let from = op.old_uri.to_file_path().unwrap();
	let to = op.new_uri.to_file_path().unwrap();
	let ignore_if_exists = op.options.as_ref().map_or(false, |options| {
	!options.overwrite.unwrap_or(false) && options.ignore_if_exists.unwrap_or(false)
	});
	if ignore_if_exists && to.exists() {
	Ok(())
	} else {
	fs::rename(from, &to)
	}

But this needs to be updated to use willRenameFiles.

This causes a bug with rust analyzer for example, see #8923.

[the-mikedavis]

@pascalkuthe I know that you have been looking at this block recently. Is this something you are interested in solving? If not we could add the E-help-wanted label

[pascalkuthe]

Yeah I will try to do it all in one go (otherwise the PRs would just conflict). That's actually a useful pointer, great find! I really need to find where VScode Handels all of this but I can't find the right place in the codebase.

[matoous]

@pascalkuthe https://github.com/microsoft/vscode/blob/main/src/vs/workbench/api/common/extHostFileSystemEventService.ts#L248 I think this might be the place to start. Would be nice to end up with something similar in Helix (as I was recently looking at willSave which could also benefit from a streamlined interface for document/file management).

[pascalkuthe]

this feels like a job for the event system TBH but until that is merged having a workaround would be nice I guess. I think I will start out just fixing this issue (and the related PR) so we can get rid of the regression. A general system like that seems perfect for the event system once that lands.