Attempting to add a new code class to a project that is not correctly set up for IWYU (such as an older project that may not have been properly modified for IWYU when upgrading) will result in the build of the project with the new class failing. The build fails because the .cpp file for the new code class is created with two #include statements on a single line.
No. The same behavior occurs in 4.20.3.
The new code class will be added to the project, but the hot reload of the project with the new class will fail.
The new code class is added to the project, and the hot reload completes successfully.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-66879 in the post.