editor.insertSnippet() messes with indenting of the SnippetString

[DanTup]

This is a very similar issue to #44200/#57093 but that fix appears to be only being applied to completions, but applying snippets causes the same issues.

Here's a repro:

vs.workspace.openTextDocument(vs.Uri.parse(`untitled:${os.tmpdir}/a.dart`)).then(async (document) => {

	const originalCode = `main() {
  // code indented with two spaces
}`;
	const editor = await vs.window.showTextDocument(document);
	await editor.edit((eb) => eb.insert(new vs.Position(0, 0), originalCode));

	const startOffset = originalCode.indexOf("// code indented with two spaces");
	const endOffset = originalCode.indexOf("\n}");
	const snippetString = new vs.SnippetString("// new code indented with two spaces\n  // newer code indented with two spaces");

	await editor.insertSnippet(snippetString, new vs.Range(document.positionAt(startOffset), document.positionAt(endOffset)));
});

This creates a doc and inserts into it the code:

main() {
  // code indented with two spaces
}

It then applies a snippet string that includes an additional line that is also indented by two spaces. However what you end up with is:

main() {
  // new code indented with two spaces
    // newer code indented with two spaces
}

The inserted line has been re-indented.

Whilst this behaviour may be useful if applying basic hard-coded strings, it's incorrect for language servers that are correctly calculating edits to leave the file indented/formatted correctly (I guess for the same reasons that left to #57093).

[DanTup]

(@jrieken FYI - this seems similar to the completion issue you resolved)

[DanTup]

@jrieken this is tagged as a feature, but I it's really a bug. Any language server calculating the correct edits exactly as required will end up with bad indenting. There's no way for an extension to really fix this without asking the language server to implement the edit incorrectly.

This was fixed for completions, just not for edits.

[DanTup]

@jrieken is this something that could easily be contributed (with a similar fix to whatever was done in completions?). As mentioned above, this is really a bug not a feature - VS Code is assuming a language extension is generating incorrect indenting and doesn't work correctly if it generates the correct indenting.

[dancojocaru2000]

Any updates on this? It's really annoying to constantly have to select and delete a huge chunk of indentation. This reason alone makes me almost want to switch to IntelliJ.

[DanTup]

It's been marked as a feature (even though it seems to surely be a bug to assume language servers don't know how to indent), so I'm not sure it'll be fixed anytime soon.

Maybe it's worth trying to work around in the extension by reading the indent level from the current line and subtracting that much whitespace from each line? 🤔 It does mean if VS Code ever does fix it, we'll be wrong in the opposite direction until we remove the workaround though.

I might have a play around and see how well it works.

[dancojocaru2000]

Programmers joke about transforming bugs into features but VS Code devs seem to have taken it literally.