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

   1 // run-rustfix
   2
   3 #![allow(
   4     unused,
   5     clippy::no_effect,
   6     clippy::redundant_closure_call,
   7     clippy::many_single_char_names,
   8     clippy::needless_pass_by_value,
   9     clippy::option_map_unit_fn
  10 )]
  11 #![warn(
  12     clippy::redundant_closure,
  13     clippy::redundant_closure_for_method_calls,
  14     clippy::needless_borrow
  15 )]
  16
  17 use std::path::PathBuf;
  18
  19 macro_rules! mac {
  20     () => {
  21         foobar()
  22     };
  23 }
  24
  25 macro_rules! closure_mac {
  26     () => {
  27         |n| foo(n)
  28     };
  29 }
  30
  31 fn main() {
  32     let a = Some(1u8).map(|a| foo(a));
  33     meta(|a| foo(a));
  34     let c = Some(1u8).map(|a| {1+2; foo}(a));
  35     true.then(|| mac!()); // don't lint function in macro expansion
  36     Some(1).map(closure_mac!()); // don't lint closure in macro expansion
  37     let _: Option<Vec<u8>> = true.then(|| vec![]); // special case vec!
  38     let d = Some(1u8).map(|a| foo((|b| foo2(b))(a))); //is adjusted?
  39     all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
  40     unsafe {
  41         Some(1u8).map(|a| unsafe_fn(a)); // unsafe fn
  42     }
  43
  44     // See #815
  45     let e = Some(1u8).map(|a| divergent(a));
  46     let e = Some(1u8).map(|a| generic(a));
  47     let e = Some(1u8).map(generic);
  48     // See #515
  49     let a: Option<Box<dyn (::std::ops::Deref<Target = [i32]>)>> =
  50         Some(vec![1i32, 2]).map(|v| -> Box<dyn (::std::ops::Deref<Target = [i32]>)> { Box::new(v) });
  51
  52     // issue #7224
  53     let _: Option<Vec<u32>> = Some(0).map(|_| vec![]);
  54 }
  55
  56 trait TestTrait {
  57     fn trait_foo(self) -> bool;
  58     fn trait_foo_ref(&self) -> bool;
  59 }
  60
  61 struct TestStruct<'a> {
  62     some_ref: &'a i32,
  63 }
  64
  65 impl<'a> TestStruct<'a> {
  66     fn foo(self) -> bool {
  67         false
  68     }
  69     unsafe fn foo_unsafe(self) -> bool {
  70         true
  71     }
  72 }
  73
  74 impl<'a> TestTrait for TestStruct<'a> {
  75     fn trait_foo(self) -> bool {
  76         false
  77     }
  78     fn trait_foo_ref(&self) -> bool {
  79         false
  80     }
  81 }
  82
  83 impl<'a> std::ops::Deref for TestStruct<'a> {
  84     type Target = char;
  85     fn deref(&self) -> &char {
  86         &'a'
  87     }
  88 }
  89
  90 fn test_redundant_closures_containing_method_calls() {
  91     let i = 10;
  92     let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
  93     let e = Some(TestStruct { some_ref: &i }).map(TestStruct::foo);
  94     let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo());
  95     let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo_ref());
  96     let e = Some(TestStruct { some_ref: &i }).map(TestTrait::trait_foo);
  97     let e = Some(&mut vec![1, 2, 3]).map(|v| v.clear());
  98     let e = Some(&mut vec![1, 2, 3]).map(std::vec::Vec::clear);
  99     unsafe {
 100         let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo_unsafe());
 101     }
 102     let e = Some("str").map(|s| s.to_string());
 103     let e = Some("str").map(str::to_string);
 104     let e = Some('a').map(|s| s.to_uppercase());
 105     let e = Some('a').map(char::to_uppercase);
 106     let e: std::vec::Vec<usize> = vec!['a', 'b', 'c'].iter().map(|c| c.len_utf8()).collect();
 107     let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(|c| c.to_ascii_uppercase()).collect();
 108     let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(char::to_ascii_uppercase).collect();
 109     let p = Some(PathBuf::new());
 110     let e = p.as_ref().and_then(|s| s.to_str());
 111     let c = Some(TestStruct { some_ref: &i })
 112         .as_ref()
 113         .map(|c| c.to_ascii_uppercase());
 114
 115     fn test_different_borrow_levels<T>(t: &[&T])
 116     where
 117         T: TestTrait,
 118     {
 119         t.iter().filter(|x| x.trait_foo_ref());
 120         t.iter().map(|x| x.trait_foo_ref());
 121     }
 122
 123     let mut some = Some(|x| x * x);
 124     let arr = [Ok(1), Err(2)];
 125     let _: Vec<_> = arr.iter().map(|x| x.map_err(|e| some.take().unwrap()(e))).collect();
 126 }
 127
 128 struct Thunk<T>(Box<dyn FnMut() -> T>);
 129
 130 impl<T> Thunk<T> {
 131     fn new<F: 'static + FnOnce() -> T>(f: F) -> Thunk<T> {
 132         let mut option = Some(f);
 133         // This should not trigger redundant_closure (#1439)
 134         Thunk(Box::new(move || option.take().unwrap()()))
 135     }
 136
 137     fn unwrap(self) -> T {
 138         let Thunk(mut f) = self;
 139         f()
 140     }
 141 }
 142
 143 fn foobar() {
 144     let thunk = Thunk::new(|| println!("Hello, world!"));
 145     thunk.unwrap()
 146 }
 147
 148 fn meta<F>(f: F)
 149 where
 150     F: Fn(u8),
 151 {
 152     f(1u8)
 153 }
 154
 155 fn foo(_: u8) {}
 156
 157 fn foo2(_: u8) -> u8 {
 158     1u8
 159 }
 160
 161 fn all<X, F>(x: &[X], y: &X, f: F) -> bool
 162 where
 163     F: Fn(&X, &X) -> bool,
 164 {
 165     x.iter().all(|e| f(e, y))
 166 }
 167
 168 fn below(x: &u8, y: &u8) -> bool {
 169     x < y
 170 }
 171
 172 unsafe fn unsafe_fn(_: u8) {}
 173
 174 fn divergent(_: u8) -> ! {
 175     unimplemented!()
 176 }
 177
 178 fn generic<T>(_: T) -> u8 {
 179     0
 180 }
 181
 182 fn passes_fn_mut(mut x: Box<dyn FnMut()>) {
 183     requires_fn_once(|| x());
 184 }
 185 fn requires_fn_once<T: FnOnce()>(_: T) {}
 186
 187 fn test_redundant_closure_with_function_pointer() {
 188     type FnPtrType = fn(u8);
 189     let foo_ptr: FnPtrType = foo;
 190     let a = Some(1u8).map(|a| foo_ptr(a));
 191 }
 192
 193 fn test_redundant_closure_with_another_closure() {
 194     let closure = |a| println!("{}", a);
 195     let a = Some(1u8).map(|a| closure(a));
 196 }
 197
 198 fn make_lazy(f: impl Fn() -> fn(u8) -> u8) -> impl Fn(u8) -> u8 {
 199     // Currently f is called when result of make_lazy is called.
 200     // If the closure is removed, f will be called when make_lazy itself is
 201     // called. This changes semantics, so the closure must stay.
 202     Box::new(move |x| f()(x))
 203 }
 204
 205 fn call<F: FnOnce(&mut String) -> String>(f: F) -> String {
 206     f(&mut "Hello".to_owned())
 207 }
 208 fn test_difference_in_mutability() {
 209     call(|s| s.clone());
 210 }
 211
 212 struct Bar;
 213 impl std::ops::Deref for Bar {
 214     type Target = str;
 215     fn deref(&self) -> &str {
 216         "hi"
 217     }
 218 }
 219
 220 fn test_deref_with_trait_method() {
 221     let _ = [Bar].iter().map(|s| s.to_string()).collect::<Vec<_>>();
 222 }
 223
 224 fn mutable_closure_used_again(x: Vec<i32>, y: Vec<i32>, z: Vec<i32>) {
 225     let mut res = Vec::new();
 226     let mut add_to_res = |n| res.push(n);
 227     x.into_iter().for_each(|x| add_to_res(x));
 228     y.into_iter().for_each(|x| add_to_res(x));
 229     z.into_iter().for_each(|x| add_to_res(x));
 230 }
 231
 232 fn mutable_closure_in_loop() {
 233     let mut value = 0;
 234     let mut closure = |n| value += n;
 235     for _ in 0..5 {
 236         Some(1).map(|n| closure(n));
 237     }
 238 }