setup-dotnet/.github/csc.json

{
    "problemMatcher": [
        {
            "owner": "csc",
            "pattern": [
                {
                    "regexp": "^([^\s].*)\((\d+)(?:,\d+|,\d+,\d+)?\):\s+(error|warning)\s+([a-zA-Z]+(?<!MSB)\d+):\s*(.*?)\s+\[(.*?)\]$",
                    "file": 1,
                    "line": 2,
                    "severity": 3,
                    "code": 4,
                    "message": 5,
                    "fromPath": 6
                }
            ]
        }
    ]
}