Slice of structs with slice members fails to be set coherently

[grasshopper47]

Aim

@vezenovm continuation of #3476

global BEGIN_OBJECT    : u8 = 0x7B; // { left curly bracket
global END_OBJECT      : u8 = 0x7D; // } right curly bracket
global BACKSLASH       : u8 = 0x5C; // \ reverse solidus

global chars =
[
    "\0","\0","\0","\0","\0","\0","\0","\0","\0","\t","\n","\0","\0","\r","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0","\0",
    " ","!","\"","#","$","%","&","'","(",")","*","+",",","-",".","/",
    "0","1","2","3","4","5","6","7","8","9",
    ":",";","<","=",">","?","@",
    "A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z",
    "[","\\","]","^","_","`",
    "a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z",
    "{","|","}","~"
];

struct Property
{
    key : [u8]
,   value : [u8]
}

type Object = [Property];

struct JSON
{
    doc : Object
}

impl Property
{
    unconstrained
    fn print(self)
    {
        dep::std::println("{\nkey");
        for byte in self.key { let c = chars[byte]; dep::std::println(f"    {c}"); }
        dep::std::println("}");

        dep::std::println("value\n{");

        let mut object = false;
        for byte in self.value
        {
            if (object & (byte != END_OBJECT) & (byte != BACKSLASH))
            {
                dep::std::println(f"        {byte}");
            }
            else
            {
                let c = chars[byte];
                dep::std::println(f"    {c}");

                object = (byte == BEGIN_OBJECT);
            }
        }

        dep::std::println("}");
    }
}

impl JSON
{
    unconstrained
    fn store(mut self, prop : Property) -> Object
    {
        for i in 0..self.doc.len() { self.doc[i].value = prop.value; }

        self.doc
    }
}

#[test]
unconstrained
fn property_key_number_and_key_array_object()
{
    let mut json = JSON { doc: [ Property { key: "a".as_bytes(), value: "1".as_bytes() } ] };
    let mut prop = Property { key: "a".as_bytes(), value:"123".as_bytes() }; // remove the `mut` keyword here, and the output will be different

    json.doc = json.store(prop);

    for prop in json.doc { prop.print(); }
}

Expected Behavior

the expected output is:

key
{
    a
}
value
{
    1
    2
    3
}

Bug

actual output

key
{
    1
    
    
    a
    1
    2
    3
    
    
    
    
    
    
    
    
}
value
{
    
}

To Reproduce

Run the provided code

Installation Method

None

Nargo Version

nargo 0.19.4

Additional Context

No response

Would you like to submit a PR for this Issue?

No

Support Needs

No response

[vezenovm]

Nested slices have been banned and we are leaning into BoundedVec for now #4197 due to a combination of their complexity + inefficiency in ACIR.

Slice of slices may be brought back in the future, but we want to have parity in feature across our constrained and unconstrained environment. Apologies for any inconvenience this may cause. Closing this issue for now.