Add generic args for comparison in `use_self` and `useless_conversion` lints

6 files changed, 124 insertions, 2 deletions

diff --git a/tests/ui/use_self.fixed b/tests/ui/use_self.fixed
index 1282befdfb3..631da6fe066 100644
--- a/tests/ui/use_self.fixed
+++ b/tests/ui/use_self.fixed
@@ -462,3 +462,33 @@ mod issue6818 {
         a: i32,
     }
 }
+
+mod issue7206 {
+    struct MyStruct<const C: char>;
+    impl From<MyStruct<'a'>> for MyStruct<'b'> {
+        fn from(_s: MyStruct<'a'>) -> Self {
+            Self
+        }
+    }
+
+    // keep linting non-`Const` generic args
+    struct S<'a> {
+        inner: &'a str,
+    }
+
+    struct S2<T> {
+        inner: T,
+    }
+
+    impl<T> S2<T> {
+        fn new() -> Self {
+            unimplemented!();
+        }
+    }
+
+    impl<'a> S2<S<'a>> {
+        fn new_again() -> Self {
+            Self::new()
+        }
+    }
+}
diff --git a/tests/ui/use_self.rs b/tests/ui/use_self.rs
index 7aaac7b2414..7a10d755faa 100644
--- a/tests/ui/use_self.rs
+++ b/tests/ui/use_self.rs
@@ -462,3 +462,33 @@ mod issue6818 {
         a: i32,
     }
 }
+
+mod issue7206 {
+    struct MyStruct<const C: char>;
+    impl From<MyStruct<'a'>> for MyStruct<'b'> {
+        fn from(_s: MyStruct<'a'>) -> Self {
+            Self
+        }
+    }
+
+    // keep linting non-`Const` generic args
+    struct S<'a> {
+        inner: &'a str,
+    }
+
+    struct S2<T> {
+        inner: T,
+    }
+
+    impl<T> S2<T> {
+        fn new() -> Self {
+            unimplemented!();
+        }
+    }
+
+    impl<'a> S2<S<'a>> {
+        fn new_again() -> Self {
+            S2::new()
+        }
+    }
+}
diff --git a/tests/ui/use_self.stderr b/tests/ui/use_self.stderr
index a32a9b9157d..cf6222c9b45 100644
--- a/tests/ui/use_self.stderr
+++ b/tests/ui/use_self.stderr
@@ -162,5 +162,11 @@ error: unnecessary structure name repetition
 LL |             A::new::<submod::B>(submod::B {})
    |             ^ help: use the applicable keyword: `Self`
 
-error: aborting due to 27 previous errors
+error: unnecessary structure name repetition
+  --> $DIR/use_self.rs:491:13
+   |
+LL |             S2::new()
+   |             ^^ help: use the applicable keyword: `Self`
+
+error: aborting due to 28 previous errors
 
diff --git a/tests/ui/useless_conversion.fixed b/tests/ui/useless_conversion.fixed
index 03977de9455..76aa82068d6 100644
--- a/tests/ui/useless_conversion.fixed
+++ b/tests/ui/useless_conversion.fixed
@@ -70,4 +70,23 @@ fn main() {
     let a: i32 = 1;
     let b: i32 = 1;
     let _ = (a + b) * 3;
+
+    // see #7205
+    let s: Foo<'a'> = Foo;
+    let _: Foo<'b'> = s.into();
+    let s2: Foo<'a'> = Foo;
+    let _: Foo<'a'> = s2;
+    let s3: Foo<'a'> = Foo;
+    let _ = s3;
+    let s4: Foo<'a'> = Foo;
+    let _ = vec![s4, s4, s4].into_iter();
+}
+
+#[derive(Copy, Clone)]
+struct Foo<const C: char>;
+
+impl From<Foo<'a'>> for Foo<'b'> {
+    fn from(_s: Foo<'a'>) -> Self {
+        Foo
+    }
 }
diff --git a/tests/ui/useless_conversion.rs b/tests/ui/useless_conversion.rs
index f6e094c1661..ccee7abb404 100644
--- a/tests/ui/useless_conversion.rs
+++ b/tests/ui/useless_conversion.rs
@@ -70,4 +70,23 @@ fn main() {
     let a: i32 = 1;
     let b: i32 = 1;
     let _ = i32::from(a + b) * 3;
+
+    // see #7205
+    let s: Foo<'a'> = Foo;
+    let _: Foo<'b'> = s.into();
+    let s2: Foo<'a'> = Foo;
+    let _: Foo<'a'> = s2.into();
+    let s3: Foo<'a'> = Foo;
+    let _ = Foo::<'a'>::from(s3);
+    let s4: Foo<'a'> = Foo;
+    let _ = vec![s4, s4, s4].into_iter().into_iter();
+}
+
+#[derive(Copy, Clone)]
+struct Foo<const C: char>;
+
+impl From<Foo<'a'>> for Foo<'b'> {
+    fn from(_s: Foo<'a'>) -> Self {
+        Foo
+    }
 }
diff --git a/tests/ui/useless_conversion.stderr b/tests/ui/useless_conversion.stderr
index 26a33595031..e6760f700f3 100644
--- a/tests/ui/useless_conversion.stderr
+++ b/tests/ui/useless_conversion.stderr
@@ -70,5 +70,23 @@ error: useless conversion to the same type: `i32`
 LL |     let _ = i32::from(a + b) * 3;
    |             ^^^^^^^^^^^^^^^^ help: consider removing `i32::from()`: `(a + b)`
 
-error: aborting due to 11 previous errors
+error: useless conversion to the same type: `Foo<'a'>`
+  --> $DIR/useless_conversion.rs:78:23
+   |
+LL |     let _: Foo<'a'> = s2.into();
+   |                       ^^^^^^^^^ help: consider removing `.into()`: `s2`
+
+error: useless conversion to the same type: `Foo<'a'>`
+  --> $DIR/useless_conversion.rs:80:13
+   |
+LL |     let _ = Foo::<'a'>::from(s3);
+   |             ^^^^^^^^^^^^^^^^^^^^ help: consider removing `Foo::<'a'>::from()`: `s3`
+
+error: useless conversion to the same type: `std::vec::IntoIter<Foo<'a'>>`
+  --> $DIR/useless_conversion.rs:82:13
+   |
+LL |     let _ = vec![s4, s4, s4].into_iter().into_iter();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `vec![s4, s4, s4].into_iter()`
+
+error: aborting due to 14 previous errors