From f058e255db5647299e0d411b9c290ed7febde536 Mon Sep 17 00:00:00 2001
From: ticki <ticki@users.noreply.github.com>
Date: Tue, 19 Jul 2016 13:29:05 +0200
Subject: [PATCH] Const-ify certain methods on std::time::Duration

---
 src/libstd/time/duration.rs | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/libstd/time/duration.rs b/src/libstd/time/duration.rs
index 7c3240b4a40c4..e3b96bda6f10f 100644
--- a/src/libstd/time/duration.rs
+++ b/src/libstd/time/duration.rs
@@ -42,7 +42,8 @@ const MILLIS_PER_SEC: u64 = 1_000;
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
 pub struct Duration {
     secs: u64,
-    nanos: u32, // Always 0 <= nanos < NANOS_PER_SEC
+    /// Always 0 <= nanos < NANOS_PER_SEC
+    nanos: u32,
 }
 
 impl Duration {
@@ -52,24 +53,26 @@ impl Duration {
     /// If the nanoseconds is greater than 1 billion (the number of nanoseconds
     /// in a second), then it will carry over into the seconds provided.
     #[stable(feature = "duration", since = "1.3.0")]
-    pub fn new(secs: u64, nanos: u32) -> Duration {
-        let secs = secs + (nanos / NANOS_PER_SEC) as u64;
-        let nanos = nanos % NANOS_PER_SEC;
-        Duration { secs: secs, nanos: nanos }
+    pub const fn new(secs: u64, nanos: u32) -> Duration {
+        Duration {
+            secs: secs + (nanos / NANOS_PER_SEC) as u64,
+            nanos: nanos % NANOS_PER_SEC
+        }
     }
 
     /// Creates a new `Duration` from the specified number of seconds.
     #[stable(feature = "duration", since = "1.3.0")]
-    pub fn from_secs(secs: u64) -> Duration {
+    pub const fn from_secs(secs: u64) -> Duration {
         Duration { secs: secs, nanos: 0 }
     }
 
     /// Creates a new `Duration` from the specified number of milliseconds.
     #[stable(feature = "duration", since = "1.3.0")]
-    pub fn from_millis(millis: u64) -> Duration {
-        let secs = millis / MILLIS_PER_SEC;
-        let nanos = ((millis % MILLIS_PER_SEC) as u32) * NANOS_PER_MILLI;
-        Duration { secs: secs, nanos: nanos }
+    pub const fn from_millis(millis: u64) -> Duration {
+        Duration {
+            secs: millis / MILLIS_PER_SEC
+            nanos: ((millis % MILLIS_PER_SEC) as u32) * NANOS_PER_MILLI
+        }
     }
 
     /// Returns the number of whole seconds represented by this duration.