[Feature] Support structs on input parameters when calling transitions from program

[prajwolrg]

🚀 Feature

Support seamless passing of parameters of any types between programs.

Motivation

Consider a simple program that has transition one which takes input of type A.

program_a {
   struct A;
   transition one(a: A) {}
}

Another program should be able to call this program seamlessly:

import program_a;
program_b {
   transition two(a: A) {
       program_a/one(a);
    }
}

[d0cd]

Failing code

// The 'test_program_a' program.
program test_program_a.aleo {
    struct A {
        data: [u8; 1];
    }

    mapping a_data: u8 => A;

    transition store(key: u8, data: [u8; 1]) {
        let a: A = A {
            data
        };
        return then finalize(key, a);
    }

    finalize store(key: u8, value: A) {
        Mapping::set(a_data, key, value);
    }
}

// The 'test_program_b' program.
import test_program_a.leo;

program test_program_b.aleo {
    transition store_in_a(key: u8, data: [u8; 1]) {
        test_program_a.leo/store(key, data);
    }
}

SnarkVM Error: Failed to execute instruction (call test_program_a.aleo/store r0 r1 into r2;): Struct 'A' is not defined in the program

[d0cd]

Example: Using external structs in Aleo instructions

program points.aleo;

struct point:
    x as u8;
    y as u8;

function add_:
    input r0 as point.private;
    input r1 as point.private;
    add r0.x r1.x into r2;
    add r0.y r1.y into r3;
    cast r2 r3 into r4 as point;
    output r4 as point.private;

/////////////////////////////////////////////////

import points.aleo;

program point_arithmetic.aleo;

struct point:
    x as u8;
    y as u8;

function add_two_points:
    input r0 as point.private;
    input r1 as point.private;
    call points.aleo/add_ r0 r1 into r2;
    output r2 as point.private;