question: protected String formatSourceLine ( JCDiagnostic d , int nSpaces ) { StringBuilder buf = new StringBuilder ( ) ; DiagnosticSource source = d . getDiagnosticSource ( ) ; int pos = d . getIntPosition ( ) ; if ( d . getIntPosition ( ) == Position . NOPOS ) throw new AssertionError ( ) ; String line = ( source == null ? null : source . getLine ( pos ) ) ; if ( line == null ) return "" ; buf . append ( indent ( line , nSpaces ) ) ; int col = source . getColumnNumber ( pos , false ) ; if ( config . isCaretEnabled ( ) ) { buf . append ( "\n" ) ; for ( int i = 0 ; i < col - 1 ; i ++ ) { buf . append ( ( line . charAt ( i ) == '\t' ) ? "\t" : " " ) ; } buf . append ( indent ( "^" , nSpaces ) ) ; } return buf . toString ( ) ; }
target:  Format the faulty source code line and point to the error.