Improve color name editorUnnecessary.foreground

[aeschli]

editorUnnecessary.foreground got added as a new color.
My first thought was that this is the color of an unnecessary editor.

TypeScript calls the ranges unused spans, so I suggest we use unused, not unnecessary

• editorUnusedCode.foreground
• editor.unusedCodeForeground (similar to editor.lineHighlightBackground)
• editor.unusedCodeForeground

We had some discussions in the ZRH standup that it should go along with future semantic highlights, but no proposal was made on what that would mean for the name.
@dbaeumer @jrieken @egamma

[wistcc]

I would like to take this one if you guys think this is a good first issue. Seems like I just need to rename editorUnnecessary by editorUnused on these files:

• /src/vs/editor/browser/widget/codeEditorWidget.ts
• /src/vs/editor/common/model/intervalTree.ts
• /src/vs/editor/common/services/modelServiceImpl.ts
• /src/vs/editor/common/view/editorColorRegistry.ts

[mjbvz]

Thanks @wistcc but this is not a good choice. Easy code change but we need to discuss the design of this feature more. For example, should we fade out code instead of changing it all to grey?

[mjbvz]

Falls under #51104

[reeddunkle]

@mjbvz I'm just getting up-to-speed on the change. Thanks for adding the key editorUnnecessaryCode.opacity to control the alpha variable for the fadeout.

Is there still an option to change the color or has that been removed?

[mjbvz]

No, this option was been removed when we finalized the unused variable api

[Izhaki]

@mjbvz

This is pretty bad... we used to have unused code highlighted in yellow so it is crystal clear (fading is not enough as some themes use light grey for comments etc.)

Now with 1.25.0, this feature seem to be broken (no editorUnnecessaryCode.opacity/editor.showUnused combination seems to have an effect).

Related: #51420