Replace once_cell with types from the standard library.

Cargo.lock

@@ -3135,7 +3135,6 @@ dependencies = [
  "fehler",
  "is-terminal",
  "itertools 0.12.0",
- "once_cell",
  "predicates",
  "roff",
  "rpassword",

Cargo.toml

@@ -40,7 +40,6 @@ anyhow = "1.0.18"
 chrono = "0.4.10"
 clap = { version = "4", features = ["derive", "env", "string", "wrap_help"] }
 itertools = ">=0.10, <0.13"
-once_cell = "1.17"
 sequoia-cert-store = "0.4"
 sequoia-wot = "0.9"
 tempfile = "3.1"

src/sq.rs

@@ -10,6 +10,7 @@ use anyhow::Context as _;
 use is_terminal::IsTerminal;
 
 use std::borrow::Borrow;
+use std::cell::OnceCell;
 use std::collections::btree_map::{BTreeMap, Entry};
 use std::fmt;
 use std::io;
@@ -18,7 +19,6 @@ use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use std::time::{Duration, SystemTime};
 use std::sync::Arc;
-use once_cell::unsync::OnceCell;
 
 use sequoia_openpgp as openpgp;
 
@@ -233,11 +233,10 @@ where
             primary_uid = Some(primary.userid());
         } else {
             // Special case, there is no user id.
-            use once_cell::sync::Lazy;
-            static FALLBACK: Lazy<UserID> = Lazy::new(|| {
-                UserID::from("<unknown>")
-            });
-            primary_uid = Some(&FALLBACK);
+            use std::sync::OnceLock;
+            static FALLBACK: OnceLock<UserID> = OnceLock::new();
+            primary_uid =
+                Some(FALLBACK.get_or_init(|| UserID::from("<unknown>")));
         }
     }
 

tests/sq-link.rs

@@ -1,11 +1,10 @@
 use std::path::Path;
 use std::process::ExitStatus;
-use std::sync::Mutex;
+use std::sync::{Mutex, OnceLock};
 
 use tempfile::TempDir;
 use assert_cmd::Command;
 
-use once_cell::sync::OnceCell;
 
 use sequoia_openpgp as openpgp;
 use openpgp::Result;
@@ -24,7 +23,7 @@ fn artifact(filename: &str) -> String {
 //
 // This function drives the clock forward, and ensures that every
 // operation "happens" at a different point in time.
-static TIME: OnceCell<Mutex<chrono::DateTime<chrono::Utc>>> = OnceCell::new();
+static TIME: OnceLock<Mutex<chrono::DateTime<chrono::Utc>>> = OnceLock::new();
 
 fn tick() -> String {
     let t = TIME.get_or_init(|| Mutex::new(chrono::Utc::now()));