Add tests for some cases mentioned in #135589

tests/ui/lifetimes/missing-lifetime-in-assoc-type-1.rs

@@ -0,0 +1,16 @@
+struct S;
+struct T;
+
+impl<'a> IntoIterator for &S {
+    //~^ ERROR E0207
+    //~| NOTE unconstrained lifetime parameter
+    type Item = &T;
+    //~^ ERROR in the trait associated type
+    //~| NOTE this lifetime must come from the implemented type
+    type IntoIter = std::collections::btree_map::Values<'a, i32, T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        todo!()
+    }
+}
+fn main() {}

tests/ui/lifetimes/missing-lifetime-in-assoc-type-1.stderr

@@ -0,0 +1,15 @@
+error: in the trait associated type is declared without lifetime parameters, so using a borrowed type for them requires that lifetime to come from the implemented type
+  --> $DIR/missing-lifetime-in-assoc-type-1.rs:7:17
+   |
+LL |     type Item = &T;
+   |                 ^ this lifetime must come from the implemented type
+
+error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/missing-lifetime-in-assoc-type-1.rs:4:6
+   |
+LL | impl<'a> IntoIterator for &S {
+   |      ^^ unconstrained lifetime parameter
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0207`.

tests/ui/lifetimes/missing-lifetime-in-assoc-type-2.rs

@@ -0,0 +1,14 @@
+struct S;
+struct T;
+
+impl IntoIterator for &S {
+    type Item = &T;
+    //~^ ERROR in the trait associated type
+    type IntoIter = std::collections::btree_map::Values<'a, i32, T>;
+    //~^ ERROR use of undeclared lifetime name `'a`
+
+    fn into_iter(self) -> Self::IntoIter {
+        todo!()
+    }
+}
+fn main() {}

tests/ui/lifetimes/missing-lifetime-in-assoc-type-2.stderr

@@ -0,0 +1,24 @@
+error: in the trait associated type is declared without lifetime parameters, so using a borrowed type for them requires that lifetime to come from the implemented type
+  --> $DIR/missing-lifetime-in-assoc-type-2.rs:5:17
+   |
+LL |     type Item = &T;
+   |                 ^ this lifetime must come from the implemented type
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/missing-lifetime-in-assoc-type-2.rs:7:57
+   |
+LL |     type IntoIter = std::collections::btree_map::Values<'a, i32, T>;
+   |                                                         ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL |     type IntoIter<'a> = std::collections::btree_map::Values<'a, i32, T>;
+   |                  ++++
+help: consider introducing lifetime `'a` here
+   |
+LL | impl<'a> IntoIterator for &S {
+   |     ++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0261`.

tests/ui/lifetimes/missing-lifetime-in-assoc-type-3.rs

@@ -0,0 +1,14 @@
+struct S;
+struct T;
+
+impl IntoIterator for &S {
+    type Item = &T;
+    //~^ ERROR in the trait associated type
+    type IntoIter = std::collections::btree_map::Values<i32, T>;
+    //~^ ERROR missing lifetime specifier
+
+    fn into_iter(self) -> Self::IntoIter {
+        todo!()
+    }
+}
+fn main() {}

tests/ui/lifetimes/missing-lifetime-in-assoc-type-3.stderr

@@ -0,0 +1,20 @@
+error: in the trait associated type is declared without lifetime parameters, so using a borrowed type for them requires that lifetime to come from the implemented type
+  --> $DIR/missing-lifetime-in-assoc-type-3.rs:5:17
+   |
+LL |     type Item = &T;
+   |                 ^ this lifetime must come from the implemented type
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/missing-lifetime-in-assoc-type-3.rs:7:56
+   |
+LL |     type IntoIter = std::collections::btree_map::Values<i32, T>;
+   |                                                        ^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime parameter
+   |
+LL |     type IntoIter<'a> = std::collections::btree_map::Values<'a, i32, T>;
+   |                  ++++                                       +++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0106`.

tests/ui/lifetimes/missing-lifetime-in-assoc-type-4.rs

@@ -0,0 +1,14 @@
+struct S;
+struct T;
+
+impl IntoIterator for &S {
+    type Item = &T;
+    //~^ ERROR in the trait associated type
+    type IntoIter<'a> = std::collections::btree_map::Values<'a, i32, T>;
+    //~^ ERROR lifetime parameters or bounds on type `IntoIter` do not match the trait declaration
+
+    fn into_iter(self) -> Self::IntoIter {
+        todo!()
+    }
+}
+fn main() {}

tests/ui/lifetimes/missing-lifetime-in-assoc-type-4.stderr

@@ -0,0 +1,15 @@
+error: in the trait associated type is declared without lifetime parameters, so using a borrowed type for them requires that lifetime to come from the implemented type
+  --> $DIR/missing-lifetime-in-assoc-type-4.rs:5:17
+   |
+LL |     type Item = &T;
+   |                 ^ this lifetime must come from the implemented type
+
+error[E0195]: lifetime parameters or bounds on type `IntoIter` do not match the trait declaration
+  --> $DIR/missing-lifetime-in-assoc-type-4.rs:7:18
+   |
+LL |     type IntoIter<'a> = std::collections::btree_map::Values<'a, i32, T>;
+   |                  ^^^^ lifetimes do not match type in trait
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0195`.