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+This error indicates that the compiler is unable to determine whether there is
+exactly one unique region in the set of derived region bounds.
+
+Example of erroneous code:
+
+```compile_fail,E0227
+trait Foo<'foo>: 'foo {}
+trait Bar<'bar>: 'bar {}
+
+trait FooBar<'foo, 'bar>: Foo<'foo> + Bar<'bar> {}
+
+struct Baz<'foo, 'bar> {
+    baz: dyn FooBar<'foo, 'bar>,
+}
+```
+
+Here, `baz` can have either `'foo` or `'bar` lifetimes.
+
+To resolve this error, provide an explicit lifetime:
+
+```rust
+trait Foo<'foo>: 'foo {}
+trait Bar<'bar>: 'bar {}
+
+trait FooBar<'foo, 'bar>: Foo<'foo> + Bar<'bar> {}
+
+struct Baz<'foo, 'bar, 'baz>
+where
+    'baz: 'foo + 'bar,
+{
+    obj: dyn FooBar<'foo, 'bar> + 'baz,
+}
+```