Merging Problems

Because of differences between the RPG III and RPG IV languages, the Conversion Aid must reorder certain source statements. An example of this reordering is shown in Example of Source Conversion for the RPG III source member TEST1. If you compare the placement of the data structure DS1 in Figure 221 and in Figure 222, you can see that the data structure DS1 was moved so that it precedes the record format FORMAT1.

Now suppose that the RPG III member TEST1 was split into two members, TEST2 and COPYDS1, where the data structure DS1 and the named constant CONST1 are in a copy member COPYDS1. This copy member is included in source TEST2. Figure 228 and Figure 229 show the source for TEST2 and COPYDS1 respectively.

     H                                                                    TSTPGM
     FFILE1   IF  E                    DISK                               COMM1
     FQSYSPRT O   F     132     OF    LPRINTER
     LQSYSPRT  60FL 56OL
     E                    ARR1    3   3  1               COMM2
     E                    ARR2    3   3  1
     IFORMAT1
     I              OLDNAME                         NAME
      /COPY COPYDS1
     C           ARR1,3    DSPLY
     C                     READ FORMAT1                  01
     C           NAME      DSPLY
     C                     SETON                     LR
     C                     EXCPTOUTPUT
     OQSYSPRT E   01           OUTPUT
     O                         ARR2,3    10
**
123
**
456

     I* DATA STRUCTURE COMMENT
     IDS1         DS
     I                                        1   3 FIELD1
     I* NAMED CONSTANT COMMENT
     I              'XYZ'                 C         CONST1                COMM3
     I                                        4   6 ARR1

In this situation, the Conversion Aid would convert both member TEST2 and the copy member COPYDS1 correctly. However, when the copy member is included at compile time, it will be inserted below FORMAT1, because this is where the /COPY directive is located. As a result, all source lines in the copy member COPYDS1 will get a "source record is out of sequence" error. In RPG IV, definition specifications must precede input specifications.

Note that the Conversion Aid could not move the /COPY directive above FORMAT1 because the contents of /COPY member are unknown.

There are two methods of correcting this type of problem:

1. Use the EXPCPY(*YES) option of the CVTRPGSRC command to include all /COPY members in the converted RPG IV source member.

   This approach is easy and will work most of the time. However, including the /COPY members in each source member reduces the maintainability of your application.

2. Manually correct the code after conversion using the information in the ILE RPG compiler listing and the IBM Rational Development Studio for i: ILE RPG Reference.

Other examples of this type of problem include:

• Line Specifications and Record Address Files

  In RPG III the line counter specification and the Record Address File of the extension specification are changed to keywords (RAFDATA, FORMLEN, and FORMOFL) on the file description specification. If the content of a /COPY member contains only the line counter specification and/or the Record Address File of the extension specification but not the corresponding file description specification, the Conversion Aid does not know where to insert the keywords.

• Extension Specification Arrays and Data Structure Subfields

  As mentioned in Example of Source Conversion, you are not allowed to define a standalone array and a data structure subfield with the same name in RPG IV. Therefore, as shown in the example TEST1 ( Figure 222), the Conversion Aid must merge these two definitions. However, if the array and the data structure subfield are not in the same source member (that is, one or both is in a /COPY member), this merging cannot take place and a compile-time error will result.

• Merged compile-time array and compile-time data (**) records

  As shown in the example TEST1 ( Figure 222), if compile-time arrays are merged with data structure subfield definitions, the loading of array data may be affected. To overcome this problem, compile-time array data are changed to the new **CTDATA format if at least one compile-time array is merged. However, if the arrays and the data do not reside in the same source file (that is, one or both is in a COPY member) the naming of compile-time data records using the **CTDATA format cannot proceed properly.