Description

Extending built-in CDS types such as cds.String, cds.Integer, or cds.Decimal with property annotations using the extend cds.X with (...) syntax has been removed in CDS compiler v7 (CDS 10). This form was used to add annotations or properties to built-in types globally, affecting all elements derived from them. The compiler now emits a hard error for any such extend statement. The replacement approach is to define a named derived type that adds the desired annotations and use that type in element definitions instead of the built-in type directly.

How to Check

• [ ] Run cds compile — the compiler emits a hard error for each extend cds.* statement.
• [ ] Search all .cds files for the pattern extend cds. to locate all occurrences.
• [ ] For each match, verify whether it uses the with (...) property annotation form versus a plain extend of a user entity (which is valid).

Migration Steps

1. Identify the extend cds.* statement and the annotations it adds:

   // Breaking: extending a built-in type
   extend cds.String with (@UI.Hidden: true);

2. Define a named derived type with the desired annotations:

   - extend cds.String with (@UI.Hidden: true);
   + type HiddenString : String @UI.Hidden;

3. Update element definitions that relied on the built-in type to use the derived type instead:

   entity Documents {
     key ID       : UUID;
   - internalCode : String;
   + internalCode : HiddenString;
   }

4. If the intent was to apply the annotation globally to all String elements, audit all entities and apply the annotation selectively where needed, or use an annotate statement targeting specific entities.

Notes

The extend cds.* form was a niche feature that had unpredictable effects on the compiled output due to its global scope. The named derived type approach is more explicit and maintainable. Check the CDS documentation for any additional annotation forms that may have been declared via extend cds.* in the project.