From 9876391c6dcde1c59bb1bb35d9a0b4cab1e8ddf4 Mon Sep 17 00:00:00 2001
From: Ameya Deshpande <ameyanrd@outlook.com>
Date: Tue, 21 Sep 2021 15:06:49 +0000
Subject: [PATCH] nix-vector-routing: Use `if constexpr ()` instead of `RunIf`

Since ns-3 supports C++17 constructs now, we can make use
of `if constexpr` as it evaluates the condition inside it
only for that instantiation (distinction happens at compile
time itself).

Signed-off-by: Ameya Deshpande <ameyanrd@outlook.com>
---
 .../model/nix-vector-routing.cc               | 24 +++----------------
 1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/src/nix-vector-routing/model/nix-vector-routing.cc b/src/nix-vector-routing/model/nix-vector-routing.cc
index e6b5e7654..d451a09e3 100644
--- a/src/nix-vector-routing/model/nix-vector-routing.cc
+++ b/src/nix-vector-routing/model/nix-vector-routing.cc
@@ -34,17 +34,6 @@
 
 #include "nix-vector-routing.h"
 
-/* RunIf code is a candidate for ns-3 core module */
-template <class F, class...Ts>
-void RunIf (std::true_type, F&& f, Ts&&... ts )
-{
-  f (std::forward<Ts>(ts)...);
-}
-template <class...Xs>
-void RunIf (std::false_type, Xs&&...)
-{
-}
-
 namespace ns3 {
 
 NS_LOG_COMPONENT_DEFINE ("NixVectorRouting");
@@ -417,19 +406,12 @@ NixVectorRouting<T>::GetAdjacentNetDevices (Ptr<NetDevice> netDevice, Ptr<Channe
           for (uint32_t j = 0; j < netDeviceAddresses; ++j)
             {
               IpInterfaceAddress netDeviceIfAddr = netDeviceInterface->GetAddress (j);
-              bool isNetDeviceAddrLinkLocal = false;
-              RunIf (std::is_same<Ipv6RoutingProtocol,T>{}, [&](Ipv6InterfaceAddress IfAddr, bool &isNetDeviceAddrLinkLocal)
+              if constexpr (!IsIpv4::value)
                 {
-                  if (IfAddr.GetScope () == Ipv6InterfaceAddress::LINKLOCAL)
+                  if (netDeviceIfAddr.GetScope () == Ipv6InterfaceAddress::LINKLOCAL)
                     {
-                      isNetDeviceAddrLinkLocal = true;
+                      continue;
                     }
-                },
-              netDeviceIfAddr, isNetDeviceAddrLinkLocal);
-
-              if (isNetDeviceAddrLinkLocal)
-                {
-                  continue;
                 }
               for (uint32_t k = 0; k < remoteDeviceAddresses; ++k)
                 {