openpgp: Pass a timestamp to the KeyIter instead of each filter.

  - KeyIter::revoked and KeyIter::key_flags (and its variants) didn't
    take a time stamp so they could only be used for filtering keys
    based on their current state, not their state at some time in the
    past.  Adding a time stamp to each of the filters would have fixed
    the problem, but it would have made the interface ugly: callers
    always want the same time stamp for all filters.

  - Split KeyIter into two structures: a KeyIter and a ValidKeyIter.

  - Add KeyIter::policy.  It takes a time stamp, which is then used
    for filters like `alive` and `revoked`, and it returns a
    ValidKeyIter, which exposes filters that require a time stamp.

1 files changed, 2 insertions, 2 deletions

diff --git a/openpgp/examples/generate-encrypt-decrypt.rs b/openpgp/examples/generate-encrypt-decrypt.rs
index 416a4b73..d431e99c 100644
--- a/openpgp/examples/generate-encrypt-decrypt.rs
+++ b/openpgp/examples/generate-encrypt-decrypt.rs
@@ -41,8 +41,8 @@ fn generate() -> openpgp::Result<openpgp::Cert> {
 fn encrypt(sink: &mut dyn Write, plaintext: &str, recipient: &openpgp::Cert)
            -> openpgp::Result<()> {
     // Build a vector of recipients to hand to Encryptor.
-    let mut recipients =
-        recipient.keys().alive().revoked(false)
+    let mut recipients = recipient
+        .keys().policy(None).alive().revoked(false)
         .for_transport_encryption()
         .map(|ka| ka.key().into())
         .collect::<Vec<_>>();