See below, and see Debugging a job with full prompt for information on the launch configuration.
If you do not move the source after compiling, the debug engine can find it. However, if you do move the source, you might want to add your own source path so that the debug engine can find it after it is moved.
When source cannot be found, an editor with an error message and three buttons displays. You have three options.
If the Search for duplicate source files on the path check box is selected, the Select Source File dialog box opens when multiple files are found. The dialog box displays a list of all files that are found in the source containers specified in the Source tab of the launch configuration, from which you can choose the correct source to display for the debug session.