Enabling formatOnSave doesn't cause formatting provider to be invoked during save

[DanTup]

• VSCode Version: 1.6.0
• OS Version: Windows 10

Steps to Reproduce:

1. Install Dart-Code
2. Add "editor.formatOnSave": true to user options
3. Type some Dart into a dart file
4. Press Alt+Shift+F and observe formatting work
5. Insert some whitespace
6. Press Ctrl+S

Formatting works fine when I invoke it directly, but provideDocumentFormattingEdits never gets called when I press Save.

It works fine for JSON files, so I presume there's something specific about my extension, but I can't find anything in the docs suggesting I need to do anything specific to enable this?

I'm registering my formatter on activation like this:

context.subscriptions.push(vs.languages.registerDocumentFormattingEditProvider(DART_MODE, new DartFormattingEditProvider(analyzer)));

I've got a breakpoint in the first line of provideDocumentFormattingEdits but it never seems to trigger (full code for this file is here).

[DanTup]

Is it possible this only works with a range formatter (see here)? If so, is there any way this could be changed? I can't currently provide a range formatter and since the whole file is being saved it seems like an unnecessary restriction :(

[jrieken]

Good point - it current picks range formatters first, but that an unnecessary limitation.

[DanTup]

@jrieken When you say "first", do you mean it should still fall back to the doc formatter? (It doesn't seem to, but if that's the expectation I can do some further debugging)

[jrieken]

first as in only

[DanTup]

@jrieken Thanks, works great! 👍

[ramya-rao-a]

Verified using Go extension (from source with some changes tracked in microsoft/vscode-go#540) which also uses provideDocumentFormattingEdits