Add lifetime comment

src/main.rs

@@ -1,7 +1,7 @@
 use std::collections::{HashMap, HashSet};
 
 use clap::Parser;
-use git2::{Oid, Repository, Signature};
+use git2::{Oid, Repository, Signature, Time};
 
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]
@@ -21,12 +21,17 @@ struct Args {
     #[arg(short, long)]
     /// The author/committer email to replace the old one with.
     new_email: String,
+
+    #[arg(short, long)]
+    /// A timestamp (in seconds since the epoch) at which point commits should be considered unchanged, even if it or its parents have aforementioned email.
+    cutoff: String,
 }
 
 struct State {
     repo: git2::Repository,
     rewritten: HashMap<Oid, Oid>,
     unrewritten: HashSet<Oid>,
+    cutoff_time: Time,
     args: Args,
 }
 
@@ -42,10 +47,16 @@ impl State {
         }
 
         let mut commit = self.repo.find_commit(oid).unwrap();
+        if commit.committer().when() < self.cutoff_time {
+            self.unrewritten.insert(oid);
+            return oid;
+        }
+
         // If the email address matches, we will have to rewrite this commit either way, even if parent IDs match.
         let rewrite_author = commit.author().email().unwrap() == &self.args.rewrite_email;
 
         let parent_ids: Vec<_> = commit.parent_ids().collect();
+        // This is to deal with lifetime weirdness.
         drop(commit);
 
         let mut new_parent_ids = Vec::new();
@@ -195,11 +206,13 @@ impl State {
 fn main() {
     let args = Args::parse();
     let repo = args.repo.clone();
+    let cutoff = Time::new(i64::from_str_radix(&args.cutoff, 10).unwrap(), 0);
 
     let mut state = State {
         repo: Repository::open_bare(repo).unwrap(),
         rewritten: HashMap::new(),
         unrewritten: HashSet::new(),
+        cutoff_time: cutoff,
         args,
     };