Method concat_in_place

crates/vm/src/builtins/str.rs:1501–1521

(&mut self, other: &Wtf8, vm: &VirtualMachine)

    }

    pub fn concat_in_place(&mut self, other: &Wtf8, vm: &VirtualMachine) {
        if other.is_empty() {
            return;
        }
        let mut s = Wtf8Buf::with_capacity(self.byte_len() + other.len());
        s.push_wtf8(self.as_ref());
        s.push_wtf8(other);
        if self.as_object().strong_count() == 1 {
            // SAFETY: strong_count()==1 guarantees unique ownership of this PyStr.
            // Mutating payload in place preserves semantics while avoiding PyObject reallocation.
            unsafe {
                let payload = self.payload() as *const PyStr as *mut PyStr;
                (*payload).data = PyStr::from(s).data;
                (*payload)
                    .hash
                    .store(hash::SENTINEL, atomic::Ordering::Relaxed);
            }
        } else {
            *self = PyStr::from(s).into_ref(&vm.ctx);
        }
    }

    pub fn try_into_utf8(self, vm: &VirtualMachine) -> PyResult<PyRef<PyUtf8Str>> {
        self.ensure_valid_utf8(vm)?;