use_self - add test case of #4305

Author: tnielens

tests/ui/use_self.fixed

@@ -287,3 +287,52 @@ mod generics {
         }
     }
 }
+
+mod issue4305 {
+    pub struct Error<From, To> {
+        _from: From,
+        _too: To,
+    }
+
+    pub trait From<T> {
+        type From;
+        type To;
+
+        fn from(value: T) -> Self;
+    }
+
+    pub trait TryFrom<T>
+    where
+        Self: Sized,
+    {
+        type From;
+        type To;
+
+        fn try_from(value: T) -> Result<Self, Error<Self::From, Self::To>>;
+    }
+
+    impl<F, T> TryFrom<F> for T
+    where
+        T: From<F>,
+    {
+        type From = Self;
+        type To = Self;
+
+        fn try_from(value: F) -> Result<Self, Error<Self::From, Self::To>> {
+            Ok(From::from(value))
+        }
+    }
+
+    impl From<bool> for i64 {
+        type From = bool;
+        type To = Self;
+
+        fn from(value: bool) -> Self {
+            if value {
+                100
+            } else {
+                0
+            }
+        }
+    }
+}

tests/ui/use_self.rs

@@ -287,3 +287,52 @@ mod generics {
         }
     }
 }
+
+mod issue4305 {
+    pub struct Error<From, To> {
+        _from: From,
+        _too: To,
+    }
+
+    pub trait From<T> {
+        type From;
+        type To;
+
+        fn from(value: T) -> Self;
+    }
+
+    pub trait TryFrom<T>
+    where
+        Self: Sized,
+    {
+        type From;
+        type To;
+
+        fn try_from(value: T) -> Result<Self, Error<Self::From, Self::To>>;
+    }
+
+    impl<F, T> TryFrom<F> for T
+    where
+        T: From<F>,
+    {
+        type From = T::From;
+        type To = T::To;
+
+        fn try_from(value: F) -> Result<Self, Error<Self::From, Self::To>> {
+            Ok(From::from(value))
+        }
+    }
+
+    impl From<bool> for i64 {
+        type From = bool;
+        type To = Self;
+
+        fn from(value: bool) -> Self {
+            if value {
+                100
+            } else {
+                0
+            }
+        }
+    }
+}

tests/ui/use_self.stderr

@@ -166,5 +166,17 @@ error: unnecessary structure name repetition
 LL |             Foo { value }
    |             ^^^ help: use the applicable keyword: `Self`
 
-error: aborting due to 26 previous errors
+error: unnecessary structure name repetition
+  --> $DIR/use_self.rs:318:21
+   |
+LL |         type From = T::From;
+   |                     ^^^^^^^ help: use the applicable keyword: `Self`
+
+error: unnecessary structure name repetition
+  --> $DIR/use_self.rs:319:19
+   |
+LL |         type To = T::To;
+   |                   ^^^^^ help: use the applicable keyword: `Self`
+
+error: aborting due to 28 previous errors