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

   1 #![deny(clippy::fallible_impl_from)]
   2 #![allow(clippy::uninlined_format_args)]
   3
   4 // docs example
   5 struct Foo(i32);
   6 impl From<String> for Foo {
   7     //~^ ERROR: consider implementing `TryFrom` instead
   8     fn from(s: String) -> Self {
   9         Foo(s.parse().unwrap())
  10     }
  11 }
  12
  13 struct Valid(Vec<u8>);
  14
  15 impl<'a> From<&'a str> for Valid {
  16     fn from(s: &'a str) -> Valid {
  17         Valid(s.to_owned().into_bytes())
  18     }
  19 }
  20 impl From<usize> for Valid {
  21     fn from(i: usize) -> Valid {
  22         Valid(Vec::with_capacity(i))
  23     }
  24 }
  25
  26 struct Invalid;
  27
  28 impl From<usize> for Invalid {
  29     //~^ ERROR: consider implementing `TryFrom` instead
  30     fn from(i: usize) -> Invalid {
  31         if i != 42 {
  32             panic!();
  33         }
  34         Invalid
  35     }
  36 }
  37
  38 impl From<Option<String>> for Invalid {
  39     //~^ ERROR: consider implementing `TryFrom` instead
  40     fn from(s: Option<String>) -> Invalid {
  41         let s = s.unwrap();
  42         if !s.is_empty() {
  43             panic!("42");
  44         } else if s.parse::<u32>().unwrap() != 42 {
  45             panic!("{:?}", s);
  46         }
  47         Invalid
  48     }
  49 }
  50
  51 trait ProjStrTrait {
  52     type ProjString;
  53 }
  54 impl<T> ProjStrTrait for Box<T> {
  55     type ProjString = String;
  56 }
  57 impl<'a> From<&'a mut <Box<u32> as ProjStrTrait>::ProjString> for Invalid {
  58     //~^ ERROR: consider implementing `TryFrom` instead
  59     fn from(s: &'a mut <Box<u32> as ProjStrTrait>::ProjString) -> Invalid {
  60         if s.parse::<u32>().ok().unwrap() != 42 {
  61             panic!("{:?}", s);
  62         }
  63         Invalid
  64     }
  65 }
  66
  67 struct Unreachable;
  68
  69 impl From<String> for Unreachable {
  70     fn from(s: String) -> Unreachable {
  71         if s.is_empty() {
  72             return Unreachable;
  73         }
  74         match s.chars().next() {
  75             Some(_) => Unreachable,
  76             None => unreachable!(), // do not lint the unreachable macro
  77         }
  78     }
  79 }
  80
  81 fn main() {}