From 149d77f437f2ac2f2dafa4c424a39263b5ffebdc Mon Sep 17 00:00:00 2001
From: Justus Winter <justus@sequoia-pgp.org>
Date: Thu, 13 Aug 2020 09:47:36 +0200
Subject: openpgp: Add note to enums that cannot be exhaustively matched.

---
 openpgp/src/crypto/mpi.rs | 12 ++++++++++++
 openpgp/src/policy.rs     |  3 +++
 openpgp/src/types/mod.rs  | 27 +++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/openpgp/src/crypto/mpi.rs b/openpgp/src/crypto/mpi.rs
index 66b2c09b..beda6f86 100644
--- a/openpgp/src/crypto/mpi.rs
+++ b/openpgp/src/crypto/mpi.rs
@@ -384,6 +384,9 @@ impl fmt::Debug for ProtectedMPI {
 /// the occasional elliptic curve) in [`Key`] packets.
 ///
 ///   [`Key`]: ../../packet/enum.Key.html
+///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
 #[derive(Clone, PartialEq, Eq, Hash, Debug, PartialOrd, Ord)]
 pub enum PublicKey {
     /// RSA public key.
@@ -558,6 +561,9 @@ impl Arbitrary for PublicKey {
 ///
 ///   [`Key`]: ../../packet/enum.Key.html
 ///   [`ProtectedMPI`]: struct.ProtectedMPI.html
+///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
 // Deriving Hash here is okay: PartialEq is manually implemented to
 // ensure that secrets are compared in constant-time.
 #[derive(Clone, Hash)]
@@ -811,6 +817,9 @@ impl Arbitrary for SecretKeyMaterial {
 /// [`PKESK`] packets.
 ///
 ///   [`PKESK`]: ../../packet/enum.PKESK.html
+///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
 #[derive(Clone, PartialEq, Eq, Hash, Debug, PartialOrd, Ord)]
 pub enum Ciphertext {
     /// RSA ciphertext.
@@ -901,6 +910,9 @@ impl Arbitrary for Ciphertext {
 /// [`Signature`] packets.
 ///
 ///   [`Signature`]: ../../packet/enum.Signature.html
+///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
 #[derive(Clone, PartialEq, Eq, Hash, Debug, PartialOrd, Ord)]
 pub enum Signature {
     /// RSA signature.
diff --git a/openpgp/src/policy.rs b/openpgp/src/policy.rs
index 43c448ae..b8546cf3 100644
--- a/openpgp/src/policy.rs
+++ b/openpgp/src/policy.rs
@@ -862,6 +862,9 @@ impl<'a> Policy for StandardPolicy<'a> {
 /// Key sizes put into are buckets, rounding down to the nearest
 /// bucket.  For example, a 3253-bit RSA key is categorized as
 /// `RSA3072`.
+///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
 #[derive(Clone, Debug)]
 pub enum AsymmetricAlgorithm {
     /// RSA with key sizes up to 2048-1 bit.
diff --git a/openpgp/src/types/mod.rs b/openpgp/src/types/mod.rs
index dff23cc3..8bc4009e 100644
--- a/openpgp/src/types/mod.rs
+++ b/openpgp/src/types/mod.rs
@@ -74,6 +74,9 @@ pub(crate) use timestamp::normalize_systemtime;
 /// The OpenPGP public key algorithms as defined in [Section 9.1 of
 /// RFC 4880], and [Section 5 of RFC 6637].
 ///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
+///
 /// # Examples
 ///
 /// ```rust
@@ -296,6 +299,9 @@ impl PublicKeyAlgorithm {
 /// curves.  Instead, the curve is specified using an OID prepended to
 /// the key material.  We provide this type to be able to match on the
 /// curves.
+///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
 #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Curve {
     /// NIST curve P-256.
@@ -530,6 +536,9 @@ impl Arbitrary for Curve {
 ///
 ///   [`SymmetricAlgorithm::from`]: https://doc.rust-lang.org/std/convert/trait.From.html
 ///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
+///
 /// # Examples
 ///
 /// Use `SymmetricAlgorithm` to set the preferred symmetric algorithms on a signature:
@@ -686,6 +695,9 @@ impl Arbitrary for SymmetricAlgorithm {
 ///
 ///   [`AEADAlgorithm::from`]: https://doc.rust-lang.org/std/convert/trait.From.html
 ///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
+///
 /// This feature is [experimental](../index.html#experimental-features).
 ///
 /// # Examples
@@ -796,6 +808,9 @@ impl Arbitrary for AEADAlgorithm {
 ///
 ///   [Section 9.3 of RFC 4880]: https://tools.ietf.org/html/rfc4880#section-9.3
 ///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
+///
 /// # Examples
 ///
 /// Use `CompressionAlgorithm` to set the preferred compressions algorithms on
@@ -938,6 +953,9 @@ impl Arbitrary for CompressionAlgorithm {
 
 /// The OpenPGP hash algorithms as defined in [Section 9.4 of RFC 4880].
 ///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
+///
 /// # Examples
 ///
 /// Use `HashAlgorithm` to set the preferred hash algorithms on a signature:
@@ -1075,6 +1093,9 @@ impl Arbitrary for HashAlgorithm {
 ///
 ///   [Section 5.2.1 of RFC 4880]: https://tools.ietf.org/html/rfc4880#section-5.2.1
 ///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
+///
 /// # Examples
 ///
 /// Use `SignatureType` to create a timestamp signature:
@@ -1235,6 +1256,9 @@ impl Arbitrary for SignatureType {
 ///
 ///   [Section 5.2.3.23 of RFC 4880]: https://tools.ietf.org/html/rfc4880#section-5.2.3.23
 ///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
+///
 /// # Examples
 ///
 /// ```rust
@@ -1496,6 +1520,9 @@ impl ReasonForRevocation {
 ///
 ///   [Section 5.9 of RFC 4880]: https://tools.ietf.org/html/rfc4880#section-5.9
 ///
+/// Note: This enum cannot be exhaustively matched to allow future
+/// extensions.
+///
 /// # Examples
 ///
 /// Construct a new [`Message`] containing one text literal packet:
-- 
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