Implement textDocument/rename

[olafurpg]

The rename request is sent from the client to the server to perform a workspace-wide rename of a symbol. https://microsoft.github.io/language-server-protocol/specification#textDocument_rename

Some challenges:

• overridden methods, should we rename only the focused symbol or all overrides + their implementations? IntelliJ lets you choose the behavior but this UI is not available in LSP (although we can optionally implement it for VS Code).
• broken code, should we require the sources to compile successfully? I vote for always renaming even in the presence of broken code.

[olafurpg]

Blocked by fix in scalameta/scalameta#1859 to handle renaming of overridden methods in anonymous classes

[olafurpg]

Up for debate: should "rename symbol" work for symbols that are not defined in the workspace? For example, should it be possible to rename references to a class defined in library dependencies? In IntelliJ, the symbol must be defined in the workspace but sometimes this limitation might be undesirable.

[gabro]

@olafurpg I'm a bit puzzled by the use case.

If the symbol is defined in a dependency, wouldn't renaming references to that symbol just break the usage site?
I'm sure I'm missing something, can you provide an example?

[olafurpg]

I think you are right, we should restrict rename for symbols that are defined in the workspace.

[cb372]

Is anyone currently working on this?

Just as an anecdotal data point, I just watched a colleague try VS Code + Metals for the first time, discover that they couldn't rename symbols, and switch back to IntelliJ within 5 minutes 😢

[tgodzik]

@olafurpg started to work on some necessary work with goto implementation, but not sure when he will be able to finish this. We will most likely plan something after he gets back.