.github/problemMatcher/grepMatcherWarning.json

{
    "problemMatcher": [
        {
            "owner": "grepMatcher-warning",
            "severity": "warning",
            "pattern": [
                {
                    "regexp": "^(.+):([0-9]+):(.+)$",
                    "file": 1,
                    "line": 2,
                    "message": 3
                }
            ]
        }
    ]
}