src/tools/clippy/tests/ui/to_string_in_display.rs

   1 #![warn(clippy::to_string_in_display)]
   2 #![allow(clippy::inherent_to_string_shadow_display, clippy::to_string_in_format_args)]
   3
   4 use std::fmt;
   5
   6 struct A;
   7 impl A {
   8     fn fmt(&self) {
   9         self.to_string();
  10     }
  11 }
  12
  13 trait B {
  14     fn fmt(&self) {}
  15 }
  16
  17 impl B for A {
  18     fn fmt(&self) {
  19         self.to_string();
  20     }
  21 }
  22
  23 impl fmt::Display for A {
  24     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  25         write!(f, "{}", self.to_string())
  26     }
  27 }
  28
  29 fn fmt(a: A) {
  30     a.to_string();
  31 }
  32
  33 struct C;
  34
  35 impl C {
  36     fn to_string(&self) -> String {
  37         String::from("I am C")
  38     }
  39 }
  40
  41 impl fmt::Display for C {
  42     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  43         write!(f, "{}", self.to_string())
  44     }
  45 }
  46
  47 enum D {
  48     E(String),
  49     F,
  50 }
  51
  52 impl std::fmt::Display for D {
  53     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  54         match &self {
  55             Self::E(string) => write!(f, "E {}", string.to_string()),
  56             Self::F => write!(f, "F"),
  57         }
  58     }
  59 }
  60
  61 fn main() {
  62     let a = A;
  63     a.to_string();
  64     a.fmt();
  65     fmt(a);
  66
  67     let c = C;
  68     c.to_string();
  69 }