leo/docs/error-guides/parser/mut_function_input.md

Deprecated mut parameter

Example

This error occurs when a function parameter is marked as mut.

Erroneous code example:

circuit Foo {
    function bar(mut x: u8) {
        x = 0;
    }
}

The compiler will reject this code with, for example...:

Error [EPAR0370014]: function func(mut a: u32) { ... } is deprecated. Passed variables are mutable by default.
    --> test.leo:2:18
     |
   2 |     function bar(mut x: u8) {
     |                  ^^^^^

Solution

As the mut modifier is implicitly assumed, the solution is to remove the mut modifier:

circuit Foo {
    function bar(x: u8) {
        x = 0;
    }
}