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+A method or constant was implemented on a primitive type.
+
+Erroneous code example:
+
+```compile_fail,E0390
+struct Foo {
+    x: i32
+}
+
+impl *mut Foo {}
+// error: cannot define inherent `impl` for primitive types
+```
+
+This isn't allowed, but using a trait to implement a method or constant
+is a good solution.
+Example:
+
+```
+struct Foo {
+    x: i32
+}
+
+trait Bar {
+    fn bar();
+}
+
+impl Bar for *mut Foo {
+    fn bar() {} // ok!
+}
+```
+
+Instead of defining an inherent implementation on a reference, you could also
+move the reference inside the implementation:
+
+```compile_fail,E0390
+struct Foo;
+
+impl &Foo { // error: no nominal type found for inherent implementation
+    fn bar(self, other: Self) {}
+}
+```
+
+becomes
+
+```
+struct Foo;
+
+impl Foo {
+    fn bar(&self, other: &Self) {}
+}
+```