tests/ui/drop_ref.rs

   1 #![warn(clippy::drop_ref)]
   2 #![allow(clippy::toplevel_ref_arg)]
   3 #![allow(clippy::map_err_ignore)]
   4 #![allow(clippy::unnecessary_wraps)]
   5
   6 use std::mem::drop;
   7
   8 struct SomeStruct;
   9
  10 fn main() {
  11     drop(&SomeStruct);
  12
  13     let mut owned1 = SomeStruct;
  14     drop(&owned1);
  15     drop(&&owned1);
  16     drop(&mut owned1);
  17     drop(owned1); //OK
  18
  19     let reference1 = &SomeStruct;
  20     drop(reference1);
  21
  22     let reference2 = &mut SomeStruct;
  23     drop(reference2);
  24
  25     let ref reference3 = SomeStruct;
  26     drop(reference3);
  27 }
  28
  29 #[allow(dead_code)]
  30 fn test_generic_fn_drop<T>(val: T) {
  31     drop(&val);
  32     drop(val); //OK
  33 }
  34
  35 #[allow(dead_code)]
  36 fn test_similarly_named_function() {
  37     fn drop<T>(_val: T) {}
  38     drop(&SomeStruct); //OK; call to unrelated function which happens to have the same name
  39     std::mem::drop(&SomeStruct);
  40 }
  41
  42 #[derive(Copy, Clone)]
  43 pub struct Error;
  44 fn produce_half_owl_error() -> Result<(), Error> {
  45     Ok(())
  46 }
  47
  48 fn produce_half_owl_ok() -> Result<bool, ()> {
  49     Ok(true)
  50 }
  51
  52 #[allow(dead_code)]
  53 fn test_owl_result() -> Result<(), ()> {
  54     produce_half_owl_error().map_err(|_| ())?;
  55     produce_half_owl_ok().map(|_| ())?;
  56     // the following should not be linted,
  57     // we should not force users to use toilet closures
  58     // to produce owl results when drop is more convenient
  59     produce_half_owl_error().map_err(drop)?;
  60     produce_half_owl_ok().map_err(drop)?;
  61     Ok(())
  62 }
  63
  64 #[allow(dead_code)]
  65 fn test_owl_result_2() -> Result<u8, ()> {
  66     produce_half_owl_error().map_err(|_| ())?;
  67     produce_half_owl_ok().map(|_| ())?;
  68     // the following should not be linted,
  69     // we should not force users to use toilet closures
  70     // to produce owl results when drop is more convenient
  71     produce_half_owl_error().map_err(drop)?;
  72     produce_half_owl_ok().map(drop)?;
  73     Ok(1)
  74 }