[Bug] loop mismatched types found for operation

[0rphon]

🐛 Bug Report

Code snippet to reproduce

function main (
    x: u8,
) {
    for y in 0u8..10u8 {
        let z = y > x;
    }
}

Stack trace & error message

D:\Work\leo_playground>D:\Work\leo_repos\leo\target\release\leo clean && D:\Work\leo_repos\leo\target\release\leo run
      Done Finished in 5 milliseconds 

     Build Starting...
     Build Compiling main program... ("D:\\Work\\leo_playground\\src/main.leo")
      Done Finished in 6 milliseconds

Error:     -->  5:17
     |
     |                  ^^^^^
     |
     = Mismatched types found for operation `>`

Your Environment

• leo commit c47ab84
• rustc version 1.50.0
• Windows 10.0.19042 (Windows 10 Pro) [64-bit]

[ljedrz]

This is indeed the same issue / root cause as #772; the loop index is assigned the type U32 instead of U8.

[ljedrz]

Confirmed: the only thing that needs to be done is to complete the todo in ConstrainedProgram::enforce_iteration_statement; I tested it with a simple:

let uint = match variable.type_ {
    Type::Integer(IntegerType::U8) => Integer::U8(UInt8::constant(i as u8)),
    Type::Integer(IntegerType::U16) => Integer::U16(UInt16::constant(i as u16)),
    Type::Integer(IntegerType::U32) => Integer::U32(UInt32::constant(i as u32)),
    Type::Integer(IntegerType::U64) => Integer::U64(UInt64::constant(i as u64)),
    _ => unimplemented!(),
};

self.store(
    variable.id,
    ConstrainedValue::Integer(uint),
);

and the error was fixed; it would also fix #772. I'll leave this one to leo maintainers, as there's extra considerations I'm not sure about, including:

• are the index values validated (i.e. from <= to) by this point?
• how to treat negative index values?
• should i128/u128 indices be handled or rejected?

But otherwise that's the only issue; loop indices get parsed correctly.

[collinc97]

Type casting #600 has not been implemented at the gadget level yet. This bug will be blocked until that is implemented.