Gerrit

Affected Version: Gerrit v3.1.x or later

What steps will reproduce the problem?
1. Pick a change and go on the change detail page
2. Expand a diff
3. Select a portion of a line
4. Press 'c' to comment

What is the expected output?

* The portion of the line selected is highlighted
* The comment is relative to the selected portion

What do you see instead?

* No highlighting
* The comment is related to the whole line

What is the output of the JS console log (if applicable)?

N/A

What is the performance record (see https://developers.google.com/web/tools
/chrome-devtools/evaluate-performance/reference#record)(if applicable)?

N/A

Please provide any additional information below.

The problem is on:

/\*\* Gets the current selection, preferring the shadow DOM selection. \*/  
_getShadowOrDocumentSelection() {  
  // When using native shadow DOM, the selection returned by  
  // document.getSelection() cannot reference the actual DOM elements making  
  // up the diff, because they are in the shadow DOM of the gr-diff element.  
  // This takes the shadow DOM selection if one exists.  
  return this.root.getSelection ?  
    this.root.getSelection() :  
    document.getSelection();  
},  

The fallback logic isn't working on Safari, as the document.getSelection() won't return the correct selection and it will be later discarded altogether.

The functionality was fully working on Gerrit v3.0.x, hence this is a functional regression.

Attached a screencast showing the issue.

The issue has been tested with Safari Version 14.0.1 (16610.2.11.51.8) and Safari Version 14.0.2 (16610.3.7.1.9)