openpgp: Use non_exhaustive attribute.

  - Fixes #563
  - With an MSRV >= 1.40.0, we can use #[non_exhaustive], as mentioned
    in #406.
  - This is also a clippy lint:
    https://rust-lang.github.io/rust-clippy/master/index.html#manual_non_exhaustive

1 files changed, 1 insertions, 1 deletions

diff --git a/openpgp-ffi/src/error.rs b/openpgp-ffi/src/error.rs
index d1e9e962..3bfa0f5c 100644
--- a/openpgp-ffi/src/error.rs
+++ b/openpgp-ffi/src/error.rs
@@ -267,7 +267,7 @@ impl<'a> From<&'a anyhow::Error> for Status {
                     Status::InvalidKey,
                 &openpgp::Error::PolicyViolation(_, _) =>
                     Status::PolicyViolation,
-                openpgp::Error::__Nonexhaustive => unreachable!(),
+                &_ => unreachable!(), // openpgp::Error is non-exhaustive.
             }
         }