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

   1 // run-rustfix
   2 // edition:2018
   3 // aux-build:proc_macro_derive.rs
   4
   5 #![warn(clippy::use_self)]
   6 #![allow(dead_code)]
   7 #![allow(
   8     clippy::should_implement_trait,
   9     clippy::upper_case_acronyms,
  10     clippy::from_over_into,
  11     clippy::self_named_constructors
  12 )]
  13
  14 #[macro_use]
  15 extern crate proc_macro_derive;
  16
  17 fn main() {}
  18
  19 mod use_self {
  20     struct Foo {}
  21
  22     impl Foo {
  23         fn new() -> Foo {
  24             Foo {}
  25         }
  26         fn test() -> Foo {
  27             Foo::new()
  28         }
  29     }
  30
  31     impl Default for Foo {
  32         fn default() -> Foo {
  33             Foo::new()
  34         }
  35     }
  36 }
  37
  38 mod better {
  39     struct Foo {}
  40
  41     impl Foo {
  42         fn new() -> Self {
  43             Self {}
  44         }
  45         fn test() -> Self {
  46             Self::new()
  47         }
  48     }
  49
  50     impl Default for Foo {
  51         fn default() -> Self {
  52             Self::new()
  53         }
  54     }
  55 }
  56
  57 mod lifetimes {
  58     struct Foo<'a> {
  59         foo_str: &'a str,
  60     }
  61
  62     impl<'a> Foo<'a> {
  63         // Cannot use `Self` as return type, because the function is actually `fn foo<'b>(s: &'b str) ->
  64         // Foo<'b>`
  65         fn foo(s: &str) -> Foo {
  66             Foo { foo_str: s }
  67         }
  68         // cannot replace with `Self`, because that's `Foo<'a>`
  69         fn bar() -> Foo<'static> {
  70             Foo { foo_str: "foo" }
  71         }
  72
  73         // FIXME: the lint does not handle lifetimed struct
  74         // `Self` should be applicable here
  75         fn clone(&self) -> Foo<'a> {
  76             Foo { foo_str: self.foo_str }
  77         }
  78     }
  79 }
  80
  81 mod issue2894 {
  82     trait IntoBytes {
  83         fn to_bytes(self) -> Vec<u8>;
  84     }
  85
  86     // This should not be linted
  87     impl IntoBytes for u8 {
  88         fn to_bytes(self) -> Vec<u8> {
  89             vec![self]
  90         }
  91     }
  92 }
  93
  94 mod existential {
  95     struct Foo;
  96
  97     impl Foo {
  98         fn bad(foos: &[Foo]) -> impl Iterator<Item = &Foo> {
  99             foos.iter()
 100         }
 101
 102         fn good(foos: &[Self]) -> impl Iterator<Item = &Self> {
 103             foos.iter()
 104         }
 105     }
 106 }
 107
 108 mod tuple_structs {
 109     pub struct TS(i32);
 110
 111     impl TS {
 112         pub fn ts() -> Self {
 113             TS(0)
 114         }
 115     }
 116 }
 117
 118 mod macros {
 119     macro_rules! use_self_expand {
 120         () => {
 121             fn new() -> Foo {
 122                 Foo {}
 123             }
 124         };
 125     }
 126
 127     struct Foo {}
 128
 129     impl Foo {
 130         use_self_expand!(); // Should not lint in local macros
 131     }
 132
 133     #[derive(StructAUseSelf)] // Should not lint in derives
 134     struct A;
 135 }
 136
 137 mod nesting {
 138     struct Foo {}
 139     impl Foo {
 140         fn foo() {
 141             #[allow(unused_imports)]
 142             use self::Foo; // Can't use Self here
 143             struct Bar {
 144                 foo: Foo, // Foo != Self
 145             }
 146
 147             impl Bar {
 148                 fn bar() -> Bar {
 149                     Bar { foo: Foo {} }
 150                 }
 151             }
 152
 153             // Can't use Self here
 154             fn baz() -> Foo {
 155                 Foo {}
 156             }
 157         }
 158
 159         // Should lint here
 160         fn baz() -> Foo {
 161             Foo {}
 162         }
 163     }
 164
 165     enum Enum {
 166         A,
 167         B(u64),
 168         C { field: bool },
 169     }
 170     impl Enum {
 171         fn method() {
 172             #[allow(unused_imports)]
 173             use self::Enum::*; // Issue 3425
 174             static STATIC: Enum = Enum::A; // Can't use Self as type
 175         }
 176
 177         fn method2() {
 178             let _ = Enum::B(42);
 179             let _ = Enum::C { field: true };
 180             let _ = Enum::A;
 181         }
 182     }
 183 }
 184
 185 mod issue3410 {
 186
 187     struct A;
 188     struct B;
 189
 190     trait Trait<T> {
 191         fn a(v: T) -> Self;
 192     }
 193
 194     impl Trait<Vec<A>> for Vec<B> {
 195         fn a(_: Vec<A>) -> Self {
 196             unimplemented!()
 197         }
 198     }
 199
 200     impl<T> Trait<Vec<A>> for Vec<T>
 201     where
 202         T: Trait<B>,
 203     {
 204         fn a(v: Vec<A>) -> Self {
 205             <Vec<B>>::a(v).into_iter().map(Trait::a).collect()
 206         }
 207     }
 208 }
 209
 210 #[allow(clippy::no_effect, path_statements)]
 211 mod rustfix {
 212     mod nested {
 213         pub struct A {}
 214     }
 215
 216     impl nested::A {
 217         const A: bool = true;
 218
 219         fn fun_1() {}
 220
 221         fn fun_2() {
 222             nested::A::fun_1();
 223             nested::A::A;
 224
 225             nested::A {};
 226         }
 227     }
 228 }
 229
 230 mod issue3567 {
 231     struct TestStruct {}
 232     impl TestStruct {
 233         fn from_something() -> Self {
 234             Self {}
 235         }
 236     }
 237
 238     trait Test {
 239         fn test() -> TestStruct;
 240     }
 241
 242     impl Test for TestStruct {
 243         fn test() -> TestStruct {
 244             TestStruct::from_something()
 245         }
 246     }
 247 }
 248
 249 mod paths_created_by_lowering {
 250     use std::ops::Range;
 251
 252     struct S {}
 253
 254     impl S {
 255         const A: usize = 0;
 256         const B: usize = 1;
 257
 258         async fn g() -> S {
 259             S {}
 260         }
 261
 262         fn f<'a>(&self, p: &'a [u8]) -> &'a [u8] {
 263             &p[S::A..S::B]
 264         }
 265     }
 266
 267     trait T {
 268         fn f<'a>(&self, p: &'a [u8]) -> &'a [u8];
 269     }
 270
 271     impl T for Range<u8> {
 272         fn f<'a>(&self, p: &'a [u8]) -> &'a [u8] {
 273             &p[0..1]
 274         }
 275     }
 276 }
 277
 278 // reused from #1997
 279 mod generics {
 280     struct Foo<T> {
 281         value: T,
 282     }
 283
 284     impl<T> Foo<T> {
 285         // `Self` is applicable here
 286         fn foo(value: T) -> Foo<T> {
 287             Foo::<T> { value }
 288         }
 289
 290         // `Cannot` use `Self` as a return type as the generic types are different
 291         fn bar(value: i32) -> Foo<i32> {
 292             Foo { value }
 293         }
 294     }
 295 }
 296
 297 mod issue4140 {
 298     pub struct Error<From, To> {
 299         _from: From,
 300         _too: To,
 301     }
 302
 303     pub trait From<T> {
 304         type From;
 305         type To;
 306
 307         fn from(value: T) -> Self;
 308     }
 309
 310     pub trait TryFrom<T>
 311     where
 312         Self: Sized,
 313     {
 314         type From;
 315         type To;
 316
 317         fn try_from(value: T) -> Result<Self, Error<Self::From, Self::To>>;
 318     }
 319
 320     // FIXME: Suggested fix results in infinite recursion.
 321     // impl<F, T> TryFrom<F> for T
 322     // where
 323     //     T: From<F>,
 324     // {
 325     //     type From = Self::From;
 326     //     type To = Self::To;
 327
 328     //     fn try_from(value: F) -> Result<Self, Error<Self::From, Self::To>> {
 329     //         Ok(From::from(value))
 330     //     }
 331     // }
 332
 333     impl From<bool> for i64 {
 334         type From = bool;
 335         type To = Self;
 336
 337         fn from(value: bool) -> Self {
 338             if value { 100 } else { 0 }
 339         }
 340     }
 341 }
 342
 343 mod issue2843 {
 344     trait Foo {
 345         type Bar;
 346     }
 347
 348     impl Foo for usize {
 349         type Bar = u8;
 350     }
 351
 352     impl<T: Foo> Foo for Option<T> {
 353         type Bar = Option<T::Bar>;
 354     }
 355 }
 356
 357 mod issue3859 {
 358     pub struct Foo;
 359     pub struct Bar([usize; 3]);
 360
 361     impl Foo {
 362         pub const BAR: usize = 3;
 363
 364         pub fn foo() {
 365             const _X: usize = Foo::BAR;
 366             // const _Y: usize = Self::BAR;
 367         }
 368     }
 369 }
 370
 371 mod issue4305 {
 372     trait Foo: 'static {}
 373
 374     struct Bar;
 375
 376     impl Foo for Bar {}
 377
 378     impl<T: Foo> From<T> for Box<dyn Foo> {
 379         fn from(t: T) -> Self {
 380             Box::new(t)
 381         }
 382     }
 383 }
 384
 385 mod lint_at_item_level {
 386     struct Foo {}
 387
 388     #[allow(clippy::use_self)]
 389     impl Foo {
 390         fn new() -> Foo {
 391             Foo {}
 392         }
 393     }
 394
 395     #[allow(clippy::use_self)]
 396     impl Default for Foo {
 397         fn default() -> Foo {
 398             Foo::new()
 399         }
 400     }
 401 }
 402
 403 mod lint_at_impl_item_level {
 404     struct Foo {}
 405
 406     impl Foo {
 407         #[allow(clippy::use_self)]
 408         fn new() -> Foo {
 409             Foo {}
 410         }
 411     }
 412
 413     impl Default for Foo {
 414         #[allow(clippy::use_self)]
 415         fn default() -> Foo {
 416             Foo::new()
 417         }
 418     }
 419 }
 420
 421 mod issue4734 {
 422     #[repr(C, packed)]
 423     pub struct X {
 424         pub x: u32,
 425     }
 426
 427     impl From<X> for u32 {
 428         fn from(c: X) -> Self {
 429             unsafe { core::mem::transmute(c) }
 430         }
 431     }
 432 }
 433
 434 mod nested_paths {
 435     use std::convert::Into;
 436     mod submod {
 437         pub struct B {}
 438         pub struct C {}
 439
 440         impl Into<C> for B {
 441             fn into(self) -> C {
 442                 C {}
 443             }
 444         }
 445     }
 446
 447     struct A<T> {
 448         t: T,
 449     }
 450
 451     impl<T> A<T> {
 452         fn new<V: Into<T>>(v: V) -> Self {
 453             Self { t: Into::into(v) }
 454         }
 455     }
 456
 457     impl A<submod::C> {
 458         fn test() -> Self {
 459             A::new::<submod::B>(submod::B {})
 460         }
 461     }
 462 }
 463
 464 mod issue6818 {
 465     #[derive(serde::Deserialize)]
 466     struct A {
 467         a: i32,
 468     }
 469 }
 470
 471 mod issue7206 {
 472     struct MyStruct<const C: char>;
 473     impl From<MyStruct<'a'>> for MyStruct<'b'> {
 474         fn from(_s: MyStruct<'a'>) -> Self {
 475             Self
 476         }
 477     }
 478
 479     // keep linting non-`Const` generic args
 480     struct S<'a> {
 481         inner: &'a str,
 482     }
 483
 484     struct S2<T> {
 485         inner: T,
 486     }
 487
 488     impl<T> S2<T> {
 489         fn new() -> Self {
 490             unimplemented!();
 491         }
 492     }
 493
 494     impl<'a> S2<S<'a>> {
 495         fn new_again() -> Self {
 496             S2::new()
 497         }
 498     }
 499 }
 500
 501 mod self_is_ty_param {
 502     trait Trait {
 503         type Type;
 504         type Hi;
 505
 506         fn test();
 507     }
 508
 509     impl<I> Trait for I
 510     where
 511         I: Iterator,
 512         I::Item: Trait, // changing this to Self would require <Self as Iterator>
 513     {
 514         type Type = I;
 515         type Hi = I::Item;
 516
 517         fn test() {
 518             let _: I::Item;
 519             let _: I; // this could lint, but is questionable
 520         }
 521     }
 522 }