Allow to diff dirty files to their version on disk

[prawnsalad]

Indicators showing that I have a modified open is great but I may forget what exactly has been changed before I save the file. The context menu for both or either the editor window and Working Files list could have an option to show a diff of some sort between the saved and unsaved file contents.

[bpasero]

I think this would make a great extension once we have support to open a diff editor.

[jithurjacob]

Any progress on this feature ?

[bpasero]

This issue is currently assigned to the backlog. Every sprint we pick items from the backlog to plan for the current iteration. Please see https://github.com/Microsoft/vscode/wiki/Issue-Tracking#planning

[hoovercj]

I briefly looked into this and have a questoin: is there an easy way to open the file as it is on the disk without the changes? Using the URI of the current editor opens a file with the unsaved changes.

I was able to use a textdocumentprovider that read the file contents from disk, but then that side didn't have text highlighting because it was a text document.

[JohnArcher]

Just to give a (visual) reference for this really cool feature: Sublime Text has implemented that feature long time ago - just edit a file, right click and click "Show unsaved changes" from the context menu. Very handy feature which saves some time when you can't remember what you did exactly.

[bpasero]

I would be open to a PR here, I think it is not a lot of work. Some pointers:

• register a new text document content provider to be able to open the left hand side of the diff editor to be the file on disk (pointers: saveErrorHandler)
• register a new action to diff the current editor with the resource that can be handled with from the text document content provider (similar to CompareResourcesAction)

Related to: #7278