@danielmaion: Check this post for someone having similar issues: Sonarswift code coverage - #7 by Lena
which references a github issue too: Update xccov-to-sonarqube-generic.sh for xcode 11 by emanuelschmoczer · Pull Request #64 · SonarSource/sonar-scanning-examples · GitHub
I was able to successfully run the code coverage script on my macOS 10.15.7 in the Swift code coverage example repo: Xcode 12.1, but I got a bunch of warnings, which look harmless. The code coverage file was created. Maybe test the script on this example repo first and see what results you get.
$ ./xccov-to-sonarqube-generic.sh Build/Logs/Test/*.xcresult/ > sonarqube-generic-coverage.xml
2020-10-25 12:31:59.817 xccov[17717:2117195] Requested but did not find extension point with identifier Xcode.IDEFoundation.IDEResultKitSerializationConverter
2020-10-25 12:32:00.392 xccov[17719:2117257] Requested but did not find extension point with identifier Xcode.IDEFoundation.IDEResultKitSerializationConverter
2020-10-25 12:32:00.610 xccov[17721:2117318] Requested but did not find extension point with identifier Xcode.IDEFoundation.IDEResultKitSerializationConverter
2020-10-25 12:32:00.738 xccov[17723:2117380] Requested but did not find extension point with identifier Xcode.IDEFoundation.IDEResultKitSerializationConverter
2020-10-25 12:32:00.864 xccov[17725:2117439] Requested but did not find extension point with identifier Xcode.IDEFoundation.IDEResultKitSerializationConverter
2020-10-25 12:32:00.991 xccov[17727:2117502] Requested but did not find extension point with identifier Xcode.IDEFoundation.IDEResultKitSerializationConverter
2020-10-25 12:32:01.121 xccov[17729:2117562] Requested but did not find extension point with identifier Xcode.IDEFoundation.IDEResultKitSerializationConverter
2020-10-25 12:32:01.258 xccov[17731:2117623] Requested but did not find extension point with identifier Xcode.IDEFoundation.IDEResultKitSerializationConverter
$ cat sonarqube-generic-coverage.xml
<coverage version="1">
<file path="/Users/jting/Projects/sonar-scanning-examples/swift-coverage/swift-coverage-example/swift-coverage-example/AppDelegate.swift">
<lineToCover lineNumber="17" covered="true"/>
<lineToCover lineNumber="18" covered="true"/>
<lineToCover lineNumber="19" covered="true"/>
<lineToCover lineNumber="21" covered="false"/>
<lineToCover lineNumber="22" covered="false"/>
<lineToCover lineNumber="23" covered="false"/>
<lineToCover lineNumber="29" covered="true"/>
<lineToCover lineNumber="30" covered="true"/>
<lineToCover lineNumber="31" covered="false"/>
...
EDIT: I see people commenting on the errors I got after I ran the xccov script here.