LSP: Support for additionalTextEdits in CompletionItem

[AJenbo]

Describe your idea in details

Currently when completions are returned from the server CodeLite doesn't take into account that there can be additionalTextEdits that are part of the CompletionItem. The can bee seen in the spec.

Steps to reproduce

Trigger a completion that holds additionalTextEdits. For example, here is one from Metals:

{
  "isIncomplete": false,
  "items": [
    {
      "label": "test",
      "kind": 12,
      "detail": ": String",
      "preselect": true,
      "sortText": "00000",
      "filterText": "\"$test ",
      "insertTextFormat": 1,
      "textEdit": {
        "range": {
          "start": {
            "line": 26,
            "character": 12
          },
          "end": {
            "line": 26,
            "character": 16
          }
        },
        "newText": "test"
      },
      "additionalTextEdits": [
        {
          "range": {
            "start": {
              "line": 26,
              "character": 10
            },
            "end": {
              "line": 26,
              "character": 10
            }
          },
          "newText": "s"
        }
      ],
      "data": {
        "symbol": "example/Hello.test.",
        "target": "file:/Users/ckipp/Documents/scala-workspace/metals-minimal-sbt/?id\u003droot"
      }
    }
  ]
}

Currently the textEdit is applied, but the additionalTextEdits are not.

[Jarod42]

From code,
"additionalTextEdits" is only used in https://github.com/eranif/codelite/blob/master/Plugin/wxCodeCompletionBox.cpp#L753
I got suspicious warning with ch == L'•' ('character beyond the first in wide-character constant ignored').
So I suspect we don't necessary enter in that block.
But that block seems to handle only #include part. which seems not be your expected modification anyway...

[AJenbo]

To be specific I miss this when doing completion for classes in PHP and it pulls in a new class with an additional edit to insert use Namespace\Class; so pretty similar to what's already support for C #include... the above is just a sample from somewhere else that should apply equally, but I'll try and get a proper example (at that point my LSP was responding with 4MB of text so made it a pretty bad example).