CtString::append_str docs say that appending to &mut self prevents method from being found

[michaeljklein]

Aim

noir/noir_stdlib/src/meta/ctstring.nr

Line 10 in 8bb3908

// Bug: using &mut self as the object results in this method not being found

impl CtString {
    // Bug: using &mut self as the object results in this method not being found
    // docs:start:append_str
    pub comptime fn append_str<let N: u32>(self, s: str<N>) -> Self {
        // docs:end:append_str
        f"{self}{s}".as_ctstring()
    }

Expected Behavior

Fix bug or else add regression test and update comment

Bug

using &mut self as the object results in this method not being found

To Reproduce

Workaround

Yes

Workaround Description

Make a copy of the CtString

Additional Context

No response

Project Impact

Nice-to-have

Blocker Context

No response

Nargo Version

No response

NoirJS Version

No response

Proving Backend Tooling & Version

No response

Would you like to submit a PR for this Issue?

None

Support Needs

No response

[asterite]

I think in a recent PR that merged I fixed that:

noir/compiler/noirc_frontend/src/node_interner.rs

Lines 2407 to 2412 in bf474c0

	// Handle auto-dereferencing `&mut T` into `T`
	if let Type::MutableReference(object) = object {
	if object.unify(typ).is_ok() {
	return true;
	}
	}

That said, I'm not sure what's the fix here. We could change it to &mut self but self doesn't seem to mutate here 🤔

[jfecher]

The original method was written with signature fn(Self, str<N>) -> Self instead of fn(&mut Self, str<N>) to avoid passing a &mut self. So if that's fixed we can change the method to the original signature, although it'd be a breaking change now.

[michaeljklein]

@jfecher in that case, would it be useful to have a second method append_str_mut or similar?

Otherwise, I see a test for auto-dereferencing &mut T into T here.

[jfecher]

I think I'd rather make the breaking change or keep the current function than have 2 functions in the stdlib which more or less do the same thing.