perf: do not depend on iana-time-zone (#18088)

Chrono's `clock` feature pulls in `iana-time-zone` which links to macOS
core_foundation. This PR itself is not enough to get rid of
CoreFoundation. Removal depends on getting rid of security framework,
see #18071

1 files changed, 22 insertions, 0 deletions

diff --git a/cli/util/time.rs b/cli/util/time.rs
new file mode 100644
index 000000000..9c5b48b57
--- /dev/null
+++ b/cli/util/time.rs
@@ -0,0 +1,22 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+/// Identical to chrono::Utc::now() but without the system "clock"
+/// feature flag.
+///
+/// The "clock" feature flag pulls in the "iana-time-zone" crate
+/// which links to macOS's "CoreFoundation" framework which increases
+/// startup time for the CLI.
+///
+/// You can simply include this file in your project using
+/// `include!("path/to/cli/util/time.rs"))` and use it
+/// as a drop-in replacement for chrono::Utc::now().
+pub fn utc_now() -> chrono::DateTime<chrono::Utc> {
+  let now = std::time::SystemTime::now()
+    .duration_since(std::time::UNIX_EPOCH)
+    .expect("system time before Unix epoch");
+  let naive = chrono::NaiveDateTime::from_timestamp(
+    now.as_secs() as i64,
+    now.subsec_nanos(),
+  );
+  chrono::DateTime::from_utc(naive, chrono::Utc)
+}