Add error message if unimplemented subroutines are used

[kio-watanabe]

Summary

Fixed that if an unimplemented subroutine is called, an error message is output and a precompile error occurs.

Example

COBOL:

           CALL "CBL_CHANGE_DIR" USING "sample".

error message:

prog.cbl:5: Error: CBL_CHANGE_DIR not implemented

[Copilot]

Pull Request Overview

This PR ensures that if an unimplemented subroutine is invoked, a clear error message is displayed and a precompile error is triggered.

• Introduces a dedicated switch block to check for various unimplemented subroutines based on their index in the system table.
• Refactors the code to use a local variable for the literal data for clarity.

[Copilot]

[nitpick] The switch-case relies on hardcoded index values to identify unimplemented subroutines, which could be error-prone if the 'system_tab' ordering changes. Consider using named constants or an enumeration for these indices to improve code clarity and maintainability.

Suggested change

	case 2: // CBL_CHANGE_DIR
	case 3: // CBL_CHECK_FILE_EXIST
	case 4: // CBL_CLOSE_FILE
	case 5: // CBL_COPY_FILE
	case 6: // CBL_CREATE_DIR
	case 7: // CBL_CREATE_FILE
	case 8: // CBL_DELETE_DIR
	case 9: // CBL_DELETE_FILE
	case 11: // CBL_ERROR_PROC
	case 12: // CBL_EXIT_PROC
	case 13: // CBL_FLUSH_FILE
	case 14: // CBL_GET_CURRENT_DIR
	case 15: // CBL_IMP
	case 20: // CBL_OPEN_FILE
	case 22: // CBL_READ_FILE
	case 23: // CBL_RENAME_FILE
	case 26: // CBL_WRITE_FILE
	case 28: // CBL_OC_KEISEN
	case 29: // CBL_OC_ATTRIBUTE
	case 30: // C$CHDIR
	case 31: // C$COPY
	case 32: // C$DELETE
	case 33: // C$FILEINFO
	case 35: // C$GETPID
	case 36: // C$JUSTIFY
	case 38: // C$MAKEDIR
	case 39: // C$NARG
	case 40: // C$SLEEP
	case 41: // C$PARAMSIZE
	case CBL_CHANGE_DIR: // CBL_CHANGE_DIR
	case CBL_CHECK_FILE_EXIST: // CBL_CHECK_FILE_EXIST
	case CBL_CLOSE_FILE: // CBL_CLOSE_FILE
	case CBL_COPY_FILE: // CBL_COPY_FILE
	case CBL_CREATE_DIR: // CBL_CREATE_DIR
	case CBL_CREATE_FILE: // CBL_CREATE_FILE
	case CBL_DELETE_DIR: // CBL_DELETE_DIR
	case CBL_DELETE_FILE: // CBL_DELETE_FILE
	case CBL_ERROR_PROC: // CBL_ERROR_PROC
	case CBL_EXIT_PROC: // CBL_EXIT_PROC
	case CBL_FLUSH_FILE: // CBL_FLUSH_FILE
	case CBL_GET_CURRENT_DIR: // CBL_GET_CURRENT_DIR
	case CBL_IMP: // CBL_IMP
	case CBL_OPEN_FILE: // CBL_OPEN_FILE
	case CBL_READ_FILE: // CBL_READ_FILE
	case CBL_RENAME_FILE: // CBL_RENAME_FILE
	case CBL_WRITE_FILE: // CBL_WRITE_FILE
	case CBL_OC_KEISEN: // CBL_OC_KEISEN
	case CBL_OC_ATTRIBUTE: // CBL_OC_ATTRIBUTE
	case C$CHDIR: // C$CHDIR
	case C$COPY: // C$COPY
	case C$DELETE: // C$DELETE
	case C$FILEINFO: // C$FILEINFO
	case C$GETPID: // C$GETPID
	case C$JUSTIFY: // C$JUSTIFY
	case C$MAKEDIR: // C$MAKEDIR
	case C$NARG: // C$NARG
	case C$SLEEP: // C$SLEEP
	case C$PARAMSIZE: // C$PARAMSIZE

[yutaro-sakamoto]

Please see another example of kio-watanabe#6