`cannot borrow argument X as mutable` should give suggestion to fix

[Swatinem]

I’m trying to learn Rust from scratch right now, and I still have some difficulty grasping the concepts of mutability and move-semantics.

I think especially for mutability, the compiler could do a better job for suggesting fixes.
Consider the following code:

fn iter<T: Iterator<int>>(l: T) {
    for e in l {
        println!("{}", e);
    }
}

It simply says:

error: cannot borrow immutable argument `l` as mutable
    for e in l {
             ^

Which is kind of confusing. It should suggest to me that I add mut to the function argument.

[pcwalton]

+1, good suggestion.
On Aug 11, 2014 12:59 AM, "Arpad Borsos" notifications@github.com wrote:

I’m trying to learn Rust from scratch right now, and I still have some
difficulty grasping the concepts of mutability and move-semantics.

I think especially for mutability, the compiler could do a better job for
suggesting fixes.
Consider the following code:

fn iter<T: Iterator>(l: T) {
for e in l {
println!("{}", e);
}
}

It simply says:

error: cannot borrow immutable argument l as mutable
for e in l {
^

Which is kind of confusing. It should suggest to me that I add mut to the
function argument.

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