Rust compilation error，cannot borrow `*self` as mutable because it is also borrowed as immutable

[zhaoqidi]

use std::sync::Arc;

use dashmap::{DashMap};

pub struct PData{
pub titalNum:i32,
pub prompt:String,
}

pub struct Data{
pub name:String,
pub age:i32,
pub lData:DashMap<String, PData>
}

impl Data {

pub fn onVailData(&mut self){
    let mut ldata = self.lData.get_mut("liming...lData");
    let mut lldata = ldata.as_mut().unwrap().value_mut();
    lldata.titalNum = 80;
    self.CallData(lldata);
}

pub fn CallData(&mut self, pData:&mut PData){

}

}

fn main() {

let mut tData = Data{name:String::from("liming"), age:30, lData:DashMap::new()};
tData.lData.insert(String::from("liming...lData"), PData { titalNum: 10, prompt: String::from("hi,hi,hi,hi") });
tData.onVailData();

loop {

}

}

why?

[ansel-peng]

To prevent data competition, you can no longer use mutable references if you have already used immutable references in a scope.

let mut ldata = self.lData.get_mut("liming...lData");

//equal
let a= &self.lData;
let mut ldata = a.get_mut("liming...lData");

[quinedot]

More generally, you can't call a self-receiving method while holding (or passing) a reference into self if either one are mutable. It's a form of interprocedural conflict -- you can't give away exclusive (&mut) access to all of self if there are outstanding references.

The article has some workarounds.