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+Some type parameters have the same name.
+
+Erroneous code example:
+
+```compile_fail,E0403
+fn f<T, T>(s: T, u: T) {} // error: the name `T` is already used for a generic
+                          //        parameter in this item's generic parameters
+```
+
+Please verify that none of the type parameters are misspelled, and rename any
+clashing parameters. Example:
+
+```
+fn f<T, Y>(s: T, u: Y) {} // ok!
+```
+
+Type parameters in an associated item also cannot shadow parameters from the
+containing item:
+
+```compile_fail,E0403
+trait Foo<T> {
+    fn do_something(&self) -> T;
+    fn do_something_else<T: Clone>(&self, bar: T);
+}
+```