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+A trait implementation was marked as unsafe while the trait is safe.
+
+Erroneous code example:
+
+```compile_fail,E0199
+struct Foo;
+
+trait Bar { }
+
+unsafe impl Bar for Foo { } // error!
+```
+
+Safe traits should not have unsafe implementations, therefore marking an
+implementation for a safe trait unsafe will cause a compiler error. Removing
+the unsafe marker on the trait noted in the error will resolve this problem:
+
+```
+struct Foo;
+
+trait Bar { }
+
+impl Bar for Foo { } // ok!
+```