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+Trait methods currently cannot take patterns as arguments.
+
+Erroneous code example:
+
+```compile_fail,E0642
+trait Foo {
+    fn foo((x, y): (i32, i32)); // error: patterns aren't allowed
+                                //        in trait methods
+}
+```
+
+You can instead use a single name for the argument:
+
+```
+trait Foo {
+    fn foo(x_and_y: (i32, i32)); // ok!
+}
+```