Support of cross-field constraints

[shellwayxw]

Hello, is it possible to support cross-field constraints? For example:

entrypoint typedef struct _message{
header a;
body b {a.fieldA.fieldB == b.fieldC}; // This is currently not supported
} message;

[nikswamy]

Indeed, this is not currently supported directly, though we are working on ways to enhance 3D to enable it. Meanwhile, here are a couple of options:

1. A bit of inlining, i.e., inline the body b within the scope of header a's fields. Not ideal, but possible.

2. Use an out parameter to store the parts of the header that you want to refer to later.

typedef struct _A(mutable UINT32 *out) {
    UINT32 fieldA {:act *out = fieldA; };
    UINT32 fieldB;
} A;

entrypoint
typedef struct _B(mutable UINT32 *out) {
    A(out) header;
    UINT32 body {:on-success 
        var fA = *out; 
        return fA==body; };
} B;

[shellwayxw]

Thanks for the reply. The second solution should work for my case.