Different coverage results for scala 2 and scala 3

[goshacodes]

Compiler version

3.3.4

Problem

Scala 3 coverage of my project is still significantly lower than scala 2 (~ 20% for statements and 27% for branches)
I've tried to inspect reports to see differences.

1. In general Scala 3 has much more statements and branches. Why this may be so?
2. Scala 3 has much more classes then Scala 2. And looks like this is because of $anon class. I've tried to look closer and now macro generated code is also covered. IMO macro generated by some library code should not be covered by default, since library users are not testing libraries, but their own code.

So is it just more precise score and this is a desired behavior or not?

Scala 2.13 report

Scala 3 report

Scala 2.13 report

Scala 3 report

Statements

[Gedochao]

cc @KacperFKorban @sjrd

[KacperFKorban]

@goshacodes Thanks for the issue. It is probably a bug, Scala 3's coverage generation mostly just tries to be as close to Scala 2's coverage results as possible.
Can you provide some reproduction code/steps for generating your coverage data? A minimized snippet is ideal, but for coverage a repo will also do.

[goshacodes]

@KacperFKorban prepared an example

https://github.com/goshacodes/coverage-example

Reports are in the coverage-reports directory

To reproduce you need something like this:
sbt ";++2.13; coverage; test; coverageReport; ++3.3.4; test; coverageReport"

[trolley813]

Can confirm the issue in 3.5.2.

[goshacodes]

Still reproducible with 3.6.4. @KacperFKorban @Gedochao can this be prioritized, please? On huge projects there are a lot of macro generated code and this makes coverage results much worse

[Gedochao]

@goshacodes I'll see what we can do.
No promises, but looking at the roadmap, I wouldn't expect a fix before 3.8.1.

[goshacodes]

Thank you!