Comment creation fails on GitLab <= 17.7

[oleynikandrey]

Posting a review comment / draft note fails with a 400 Bad Request from the GitLab API:

{"message": {"position": ["must be a valid json schema"]}}

Environment

• gitlab.nvim commit: 80edb27 / f05aee3 (latest)
• GitLab version: 17.7.1 (self-hosted)

Root Cause
In commit 80edb27 (fix: get correct location data for comments efficiently), OldLine and NewLine were added to opt.LineRange.Start and opt.LineRange.End in cmd/app/comment_helpers.go:

opt.LineRange = &gitlab.LineRangeOptions{
    Start: &gitlab.LinePositionOptions{
        Type:     &positionData.LineRange.Start.Type,
        LineCode: &startFilenameSha,
        OldLine:  &startOldLine,
        NewLine:  &startNewLine,
    },
    ...
}

This causes the Go backend to serialize:

"line_range": {
  "start": {
    "line_code": "...",
    "type": "new",
    "old_line": 0,
    "new_line": 36
  }
}

GitLab's REST API validates position against app/validators/json_schemas/position.json. In GitLab $\le$ 17.7, line_range.start and line_range.end enforce "additionalProperties": false and only permit "line_code" and "type". As a result, including old_line or new_line causes schema validation to fail.

Fix
In cmd/app/comment_helpers.go, keep OldLine and NewLine nil / omitted from LinePositionOptions:

--- a/cmd/app/comment_helpers.go
+++ b/cmd/app/comment_helpers.go
@@ -83,14 +83,10 @@ func buildCommentPosition(commentWithPositionData RequestWithPosition) *gitlab.P
 	opt.LineRange = &gitlab.LineRangeOptions{
 		Start: &gitlab.LinePositionOptions{
 			Type:     &positionData.LineRange.Start.Type,
 			LineCode: &startFilenameSha,
-			OldLine:  &startOldLine,
-			NewLine:  &startNewLine,
 		},
 		End: &gitlab.LinePositionOptions{
 			Type:     &positionData.LineRange.End.Type,
 			LineCode: &endFilenameSha,
-			OldLine:  &endOldLine,
-			NewLine:  &endNewLine,
 		},
 	}

[jakubbortlik]

Hi Andrey, simply removing the items would be a regression for all the other users who's Gitlab supports this (these line numbers are used to display the line range in the Web UI). You are more than welcome to open a PR with a fix that will make commenting work for you again but will not break it for others.

[jakubbortlik]

Closing due to inactivity. @oleynikandrey, let me know if you want to work on this any further.