A problem matcher is a feature of Visual Studio Code. It scans the build output for error messages and converts them to errors that can be shown inside the editor or in the Problems panel.
If you have any custom build tasks, you need to manually enable suitable problem matchers for them. In order to integrate a problem matcher, add the following code to the task definition inside the tasks.json file:
"problemMatcher": [ "ProblemMatcher" ]
The following problem matchers are available for COBOL code:
"problemMatcher": [ "$COBOLAntCopybooks", "$COBOLAnt" ]
The following problem matchers are available for PL/I code: