Missing keywords

[SMadani]

The following reserved keywords are missing from the Java grammar:

• const
• goto

Furthermore, Java 10 adds local-variable type inference, so perhaps var should also be added in certain contexts?

I have been referred to this project from Visual Studio Code. The original problem can be found here.

[winstliu]

From https://docs.oracle.com/javase/tutorial/java/nutsandbolts/_keywords.html, it appears that const and goto are unused as of Java 8. Has that changed since then? If not, I don't see a reason to add them.

[SMadani]

@50Wliu Although they serve no purpose, they are still reserved keywords so an editor should be aware of their status as a keyword rather than, for example, allowing a user who is unfamiliar with the language to use them as variable names and get compilation errors.

[winstliu]

That makes sense to me, thanks for the explanation. Would you like to see them tokenized as regular keywords or for some sort of warning highlighting to be applied? /cc @sadikovi

[SMadani]

Thank you for considering this. I think it would make sense to treat them as regular keywords as nearly all other editors do not distinguish between "active" and "inactive" reserved keywords, though a warning would also be a bonus.

[sadikovi]

I think it is worth adding goto and const as regular keywords, but I do not think we should be adding var. If everyone agrees, I can open a PR for this.

[SMadani]

Great, thanks!

[fbricon]

How is var supposed to be handled then? It's technically not a keyword but a reserved type name, but we still need it to be coloured differently:

[SMadani]

It would probably make sense to colour it as a regular keyword in places where it actually works as a keyword, such as the example you provided. In general, this applies to variable declarations in methods, for loop initializers, try-with-resources and from Java 11, in lambda parameter declarations. However this is probably too complicated to support at an editor level.

[sadikovi]

As you pointed out, var is neither a reserved keyword nor a keyword at all, and could be used perfectly for a variable name, therefore we do not apply any special highlighting. We could always try adding support for var reserved type name, but not as part of this issue.