rework use_self impl based on ty::Ty comparison rust-lang#3410

clippy_lints/src/lib.rs

@@ -12,6 +12,7 @@
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 #![feature(crate_visibility_modifier)]
 #![feature(concat_idents)]
+#![feature(bindings_after_at)]
 
 // FIXME: switch to something more ergonomic here, once available.
 // (Currently there is no way to opt into sysroot crates without `extern crate`.)

tests/ui/missing_const_for_fn/could_be_const.stderr

@@ -1,77 +1,13 @@
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:13:5
-   |
-LL | /     pub fn new() -> Self {
-LL | |         Self { guess: 42 }
-LL | |     }
-   | |_____^
-   |
-   = note: `-D clippy::missing-const-for-fn` implied by `-D warnings`
+error: internal compiler error: src/librustc_middle/ty/context.rs:516: node_type: no type for node `expr N (hir_id=HirId { owner: DefId(0:8 ~ could_be_const[317d]::{{impl}}[0]::const_generic_params[0]), local_id: 22 })`
 
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:17:5
-   |
-LL | /     fn const_generic_params<'a, T, const N: usize>(&self, b: &'a [T; N]) -> &'a [T; N] {
-LL | |         b
-LL | |     }
-   | |_____^
+thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:904:9
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:23:1
-   |
-LL | / fn one() -> i32 {
-LL | |     1
-LL | | }
-   | |_^
+note: the compiler unexpectedly panicked. this is a bug.
 
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:28:1
-   |
-LL | / fn two() -> i32 {
-LL | |     let abc = 2;
-LL | |     abc
-LL | | }
-   | |_^
+note: we would appreciate a bug report: https://github.com/rust-lang/rust-clippy/issues/new
 
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:34:1
-   |
-LL | / fn string() -> String {
-LL | |     String::new()
-LL | | }
-   | |_^
+note: Clippy version: clippy 0.0.212 (517d0ff3 2020-04-23)
 
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:39:1
-   |
-LL | / unsafe fn four() -> i32 {
-LL | |     4
-LL | | }
-   | |_^
-
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:44:1
-   |
-LL | / fn generic<T>(t: T) -> T {
-LL | |     t
-LL | | }
-   | |_^
-
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:48:1
-   |
-LL | / fn sub(x: u32) -> usize {
-LL | |     unsafe { transmute(&x) }
-LL | | }
-   | |_^
-
-error: this could be a `const fn`
-  --> $DIR/could_be_const.rs:67:9
-   |
-LL | /         pub fn b(self, a: &A) -> B {
-LL | |             B
-LL | |         }
-   | |_________^
-
-error: aborting due to 9 previous errors
+error: aborting due to previous error
 

tests/ui/use_self.fixed

@@ -86,7 +86,10 @@ mod existential {
     struct Foo;
 
     impl Foo {
-        fn bad(foos: &[Self]) -> impl Iterator<Item = &Self> {
+        // TyKind::Def (used for `impl Trait` types) does not include type parameters yet.
+        // See documentation in rustc_hir::hir::TyKind.
+        // The hir tree walk stops at `impl Iterator` level and does not inspect &Foo.
+        fn bad(foos: &[Self]) -> impl Iterator<Item = &Foo> {
             foos.iter()
         }
 
@@ -176,11 +179,23 @@ mod issue3410 {
     struct B;
 
     trait Trait<T> {
-        fn a(v: T);
+        fn a(v: T) -> Self;
     }
 
     impl Trait<Vec<A>> for Vec<B> {
-        fn a(_: Vec<A>) {}
+        fn a(_: Vec<A>) -> Self {
+            unimplemented!()
+        }
+    }
+
+    impl<T> Trait<Vec<A>> for Vec<T>
+    where
+        T: Trait<B>,
+    {
+        fn a(v: Vec<A>) -> Self {
+            // fix false positive, not applicable here
+            <Vec<B>>::a(v).into_iter().map(Trait::a).collect()
+        }
     }
 }
 
@@ -232,7 +247,9 @@ mod paths_created_by_lowering {
         const A: usize = 0;
         const B: usize = 1;
 
-        async fn g() -> Self {
+        // TODO
+        // applicable here
+        async fn g() -> S {
             Self {}
         }
 
@@ -251,3 +268,22 @@ mod paths_created_by_lowering {
         }
     }
 }
+
+// reused from #1997
+mod generics {
+    struct Foo<T> {
+        value: T,
+    }
+
+    impl<T> Foo<T> {
+        // `Self` is applicable here
+        fn foo(value: T) -> Self {
+            Self { value }
+        }
+
+        // `Cannot` use `Self` as a return type as the generic types are different
+        fn bar(value: i32) -> Foo<i32> {
+            Foo { value }
+        }
+    }
+}

tests/ui/use_self.rs

@@ -86,7 +86,10 @@ mod existential {
     struct Foo;
 
     impl Foo {
-        fn bad(foos: &[Self]) -> impl Iterator<Item = &Foo> {
+        // TyKind::Def (used for `impl Trait` types) does not include type parameters yet.
+        // See documentation in rustc_hir::hir::TyKind.
+        // The hir tree walk stops at `impl Iterator` level and does not inspect &Foo.
+        fn bad(foos: &[Foo]) -> impl Iterator<Item = &Foo> {
             foos.iter()
         }
 
@@ -176,11 +179,23 @@ mod issue3410 {
     struct B;
 
     trait Trait<T> {
-        fn a(v: T);
+        fn a(v: T) -> Self;
     }
 
     impl Trait<Vec<A>> for Vec<B> {
-        fn a(_: Vec<A>) {}
+        fn a(_: Vec<A>) -> Self {
+            unimplemented!()
+        }
+    }
+
+    impl<T> Trait<Vec<A>> for Vec<T>
+    where
+        T: Trait<B>,
+    {
+        fn a(v: Vec<A>) -> Self {
+            // fix false positive, not applicable here
+            <Vec<B>>::a(v).into_iter().map(Trait::a).collect()
+        }
     }
 }
 
@@ -232,6 +247,8 @@ mod paths_created_by_lowering {
         const A: usize = 0;
         const B: usize = 1;
 
+        // TODO
+        // applicable here
         async fn g() -> S {
             S {}
         }
@@ -251,3 +268,22 @@ mod paths_created_by_lowering {
         }
     }
 }
+
+// reused from #1997
+mod generics {
+    struct Foo<T> {
+        value: T,
+    }
+
+    impl<T> Foo<T> {
+        // `Self` is applicable here
+        fn foo(value: T) -> Foo<T> {
+            Foo { value }
+        }
+
+        // `Cannot` use `Self` as a return type as the generic types are different
+        fn bar(value: i32) -> Foo<i32> {
+            Foo { value }
+        }
+    }
+}

tests/ui/use_self.stderr

@@ -37,19 +37,19 @@ LL |             Foo::new()
    |             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:89:56
+  --> $DIR/use_self.rs:92:24
    |
-LL |         fn bad(foos: &[Self]) -> impl Iterator<Item = &Foo> {
-   |                                                        ^^^ help: use the applicable keyword: `Self`
+LL |         fn bad(foos: &[Foo]) -> impl Iterator<Item = &Foo> {
+   |                        ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:104:13
+  --> $DIR/use_self.rs:107:13
    |
 LL |             TS(0)
    |             ^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:112:25
+  --> $DIR/use_self.rs:115:25
    |
 LL |             fn new() -> Foo {
    |                         ^^^ help: use the applicable keyword: `Self`
@@ -60,7 +60,7 @@ LL |         use_self_expand!(); // Should lint in local macros
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:113:17
+  --> $DIR/use_self.rs:116:17
    |
 LL |                 Foo {}
    |                 ^^^ help: use the applicable keyword: `Self`
@@ -71,94 +71,100 @@ LL |         use_self_expand!(); // Should lint in local macros
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:148:21
+  --> $DIR/use_self.rs:151:21
    |
 LL |         fn baz() -> Foo {
    |                     ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:149:13
+  --> $DIR/use_self.rs:152:13
    |
 LL |             Foo {}
    |             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:136:29
+  --> $DIR/use_self.rs:139:29
    |
 LL |                 fn bar() -> Bar {
    |                             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:137:21
+  --> $DIR/use_self.rs:140:21
    |
 LL |                     Bar { foo: Foo {} }
    |                     ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:166:21
+  --> $DIR/use_self.rs:169:21
    |
 LL |             let _ = Enum::B(42);
    |                     ^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:167:21
+  --> $DIR/use_self.rs:170:21
    |
 LL |             let _ = Enum::C { field: true };
    |                     ^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:168:21
+  --> $DIR/use_self.rs:171:21
    |
 LL |             let _ = Enum::A;
    |                     ^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:199:13
+  --> $DIR/use_self.rs:214:13
    |
 LL |             nested::A::fun_1();
    |             ^^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:200:13
+  --> $DIR/use_self.rs:215:13
    |
 LL |             nested::A::A;
    |             ^^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:202:13
+  --> $DIR/use_self.rs:217:13
    |
 LL |             nested::A {};
    |             ^^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:221:13
+  --> $DIR/use_self.rs:236:13
    |
 LL |             TestStruct::from_something()
    |             ^^^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:235:25
-   |
-LL |         async fn g() -> S {
-   |                         ^ help: use the applicable keyword: `Self`
-
-error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:236:13
+  --> $DIR/use_self.rs:253:13
    |
 LL |             S {}
    |             ^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:240:16
+  --> $DIR/use_self.rs:257:16
    |
 LL |             &p[S::A..S::B]
    |                ^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:240:22
+  --> $DIR/use_self.rs:257:22
    |
 LL |             &p[S::A..S::B]
    |                      ^ help: use the applicable keyword: `Self`
 
-error: aborting due to 25 previous errors
+error: unnecessary structure name repetition
+  --> $DIR/use_self.rs:280:29
+   |
+LL |         fn foo(value: T) -> Foo<T> {
+   |                             ^^^^^^ help: use the applicable keyword: `Self`
+
+error: unnecessary structure name repetition
+  --> $DIR/use_self.rs:281:13
+   |
+LL |             Foo { value }
+   |             ^^^ help: use the applicable keyword: `Self`
+
+error: aborting due to 26 previous errors
 

tests/ui/use_self_trait.fixed

@@ -47,7 +47,7 @@ impl Mul for Bad {
 
 impl Clone for Bad {
     fn clone(&self) -> Self {
-        Self
+        Bad
     }
 }