Debugger Issues CPF7E56 - Identifier is Ambiguous

This document explains why the debugger may issue the message CPF7E56 when trying to EVAL a variable.

Problem

When debugging a program using STRDBG, a programmer may come across message CPF7E56 when doing an EVAL on a variable. This happens when the variable name is the same as the module name.

Consider the following code:

Note: In this example, you will want to name the program/module FIELD.
 

Caution: This is an example only. IBM accepts no responsibility for its correctness.

Example

Dfield S 5a
/Free
field='Hello';
*INLR=*on;
/End-Free

If this module is named Field and placed into debug, the debugger will issue message CPF7E56 if you try to EVAL the variable 'field'. This is the full message:

Message ID . . . . . . :   CPF7E56       Severity . . . . . . . :   40        
 Message type . . . . . :   Diagnostic                                        
 Date sent  . . . . . . :   07/21/10      Time sent  . . . . . . :   18:20:07  
                                                                               
 Message . . . . :   Identifier is ambiguous                                  
 Cause . . . . . :   The identifier in position &1 of the input buffer is      
   ambiguous.                                                                  
 Recovery  . . . :   Enter the expression again with the identifier fully      
   qualified.                                                                  
 Technical description . . . . . . . . :   Refer to the language reference    
   manual for the language you are using for a technical description of the    
   grammar recognized by the Source Debugger.

This is because the name 'Field' is being generated into the debug code two times by the compiler; once as the module name and once as the variable name. When the debugger is instructed to evaluate the contents of 'Field', it searches for the name 'Field'. It finds both copies of the name and cannot distinguish between the two. It then throws the error 'Identifier is Ambiguous'.

Resolution

You should do either of the following:

1. Recompile the program/module by issuing the CRTBNDRPG command or the CRTRPGMOD command and providing a different name than FIELD

OR

2. Rename the variable so that the module/program name and variable name are different.