Enhance BOOLEAN support in SQL pre-compiler for ILE-RPG

Since the addition of the BOOLEAN data type in DB2 for i existing RPG programs might run into problems. The BOOLEAN support of the SQL pre-compiler is documented here.

Now if there is an existing table with a column "column1" of type CHAR(1) it was normal to directly store a RPG indicator in such as column:

create table table1 (
  column1 char(1) not null default '0',
  ...
);

And in RPG:

dcl-s indVar ind inz(*on);
...
exec sql insert into Table1 (Column1) values (:indVar);

This pattern was quite wide-spread as the RPG data type IND is internally represented by a CHAR(1) field which can only be '0' or '1'.

But if the same code is recompiled today, the value in Column1 might end up as 'T' (for True) and 'F' (for False), because the pre-compiler now interprets IND host variables as BOOLEAN.

      *ON  / '1' -> 'T' or 'TRUE'
      *OFF / '0' -> 'F' or 'FALSE'

The this handling is not IBM-i-ish, as it changes the behavior of a program by pure re-compilation. But existing programs - that are not re-compiled and access the same table/column - will not interpret 'T'/'F' correctly and expect '1'/'0' instead.

I propose to change the default conversion from BOOLEAN to CHAR(1) to this:

      *ON  / '1' -> '1'
      *OFF / '0' -> '0'

At least please add an pre-compiler option or an environment variable, that sets the default value for the conversion of IND host-variables in the backward compatible way.