From b33e08657ecb7949505c6eae920c83e1e84096bb Mon Sep 17 00:00:00 2001
From: Casey Bodley <cbodley@redhat.com>
Date: Wed, 15 Nov 2023 15:28:46 -0500
Subject: [PATCH] encoding: use concepts for chrono encoding

Signed-off-by: Casey Bodley <cbodley@redhat.com>
---
 src/common/ceph_time.h |  3 +++
 src/include/encoding.h | 19 +++++++------------
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/src/common/ceph_time.h b/src/common/ceph_time.h
index 6ada4d8944c..bae038862cf 100644
--- a/src/common/ceph_time.h
+++ b/src/common/ceph_time.h
@@ -529,6 +529,9 @@ struct converts_to_timespec<Clock, std::void_t<decltype(
 template <typename Clock>
 constexpr bool converts_to_timespec_v = converts_to_timespec<Clock>::value;
 
+template <typename Clock>
+concept clock_with_timespec = converts_to_timespec_v<Clock>;
+
 template<typename Rep, typename T>
 static Rep to_seconds(T t) {
   return std::chrono::duration_cast<
diff --git a/src/include/encoding.h b/src/include/encoding.h
index aac63a7e6cc..08c67c33eec 100644
--- a/src/include/encoding.h
+++ b/src/include/encoding.h
@@ -14,6 +14,7 @@
 #ifndef CEPH_ENCODING_H
 #define CEPH_ENCODING_H
 
+#include <concepts>
 #include <set>
 #include <map>
 #include <deque>
@@ -326,8 +327,7 @@ inline void decode_nohead(int len, bufferlist& s, bufferlist::const_iterator& p)
 // for time_point and duration are backward-compatible with utime_t, but
 // truncate seconds to 32 bits so are not guaranteed to round-trip.
 
-template<typename Clock, typename Duration,
-         typename std::enable_if_t<converts_to_timespec_v<Clock>>* = nullptr>
+template<clock_with_timespec Clock, typename Duration>
 void encode(const std::chrono::time_point<Clock, Duration>& t,
 	    ceph::bufferlist &bl) {
   auto ts = Clock::to_timespec(t);
@@ -338,8 +338,7 @@ void encode(const std::chrono::time_point<Clock, Duration>& t,
   encode(ns, bl);
 }
 
-template<typename Clock, typename Duration,
-         typename std::enable_if_t<converts_to_timespec_v<Clock>>* = nullptr>
+template<clock_with_timespec Clock, typename Duration>
 void decode(std::chrono::time_point<Clock, Duration>& t,
 	    bufferlist::const_iterator& p) {
   uint32_t s;
@@ -353,8 +352,7 @@ void decode(std::chrono::time_point<Clock, Duration>& t,
   t = Clock::from_timespec(ts);
 }
 
-template<typename Rep, typename Period,
-         typename std::enable_if_t<std::is_integral_v<Rep>>* = nullptr>
+template<std::integral Rep, typename Period>
 void encode(const std::chrono::duration<Rep, Period>& d,
 	    ceph::bufferlist &bl) {
   using namespace std::chrono;
@@ -364,8 +362,7 @@ void encode(const std::chrono::duration<Rep, Period>& d,
   encode(ns, bl);
 }
 
-template<typename Rep, typename Period,
-         typename std::enable_if_t<std::is_integral_v<Rep>>* = nullptr>
+template<std::integral Rep, typename Period>
 void decode(std::chrono::duration<Rep, Period>& d,
 	    bufferlist::const_iterator& p) {
   int32_t s;
@@ -378,16 +375,14 @@ void decode(std::chrono::duration<Rep, Period>& d,
 // Provide encodings for chrono::time_point and duration that use
 // the underlying representation so are guaranteed to round-trip.
 
-template <typename Rep, typename Period,
-          typename std::enable_if_t<std::is_integral_v<Rep>>* = nullptr>
+template <std::integral Rep, typename Period>
 void round_trip_encode(const std::chrono::duration<Rep, Period>& d,
                        ceph::bufferlist &bl) {
   const Rep r = d.count();
   encode(r, bl);
 }
 
-template <typename Rep, typename Period,
-          typename std::enable_if_t<std::is_integral_v<Rep>>* = nullptr>
+template <std::integral Rep, typename Period>
 void round_trip_decode(std::chrono::duration<Rep, Period>& d,
                        bufferlist::const_iterator& p) {
   Rep r;