From 0b8e768046d494624d0e191eea8183988e4c9ab7 Mon Sep 17 00:00:00 2001
From: Carlo Varni <75478407+CarloVarni@users.noreply.github.com>
Date: Tue, 29 Oct 2024 20:52:12 +0100
Subject: [PATCH] fix: Do not use requires in class EDM definition (#3731)

It looks like this is creating issues in Athena with
```console
In file included from libActsEventDict dictionary payload:146:
In file included from /cvmfs/atlas-nightlies.cern.ch/repo/sw/main--ACTS_Athena_x86_64-el9-gcc13-opt/2024-10-09T2101/Athena/25.0.20/InstallArea/x86_64-el9-gcc13-opt/include/ActsEvent/Seed.h:8:
/cvmfs/atlas-nightlies.cern.ch/repo/sw/main--ACTS_Athena_x86_64-el9-gcc13-opt/2024-10-09T2101/AthenaExternals/25.0.20/InstallArea/x86_64-el9-gcc13-opt/include/Acts/Acts/EventData/Seed.hpp:17:11: error: requires clause differs in template redeclaration
  requires(N >= 3ul)
          ^
Forward declarations from /cvmfs/atlas-nightlies.cern.ch/repo/sw/main--ACTS_Athena_x86_64-el9-gcc13-opt/2024-10-09T2101/Athena/25.0.20/InstallArea/x86_64-el9-gcc13-opt/lib/Athena.rootmap:773:18: note: previous template declaration is here
namespace Acts { template <typename external_spacepoint_t, size_t> class Seed; }
```

/cc @krasznaa

@Ragansu and @Corentin-Allaire managed to make it work by:
> removed requires(N >= 3ul) in Seed.h and Seed.ipp and recompiled ACTS
> commented out parts in CxxUtils.h which delt with std::range when __cling__ is enabled. and recompiled Athena with a modified Package Filter.

Quoting:
> For information I think part of the issue might be that Cling doesn't like the requiere in the seed definition:
> The other issue seem to be that athena redefine the std::range::end function when Cling is used (in CxxUtils/range). Probably because it was not implemented before, but now this create a conflict with newer root version I guess ?

See: https://atlas-art-data.web.cern.ch/atlas-art-data/grid-output/main/Athena/x86_64-el9-gcc13-opt/2024-10-08T2101/InDetPhysValMonitoring/test_run4_acts_vertex_PU200/tarball_logs/payload.stdout

Co-authored-by: Pierfrancesco Butti <25535240+pbutti@users.noreply.github.com>
---
 Core/include/Acts/EventData/Seed.hpp | 3 ++-
 Core/include/Acts/EventData/Seed.ipp | 6 ------
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/Core/include/Acts/EventData/Seed.hpp b/Core/include/Acts/EventData/Seed.hpp
index db93b319dcb..f3c6707b2e1 100644
--- a/Core/include/Acts/EventData/Seed.hpp
+++ b/Core/include/Acts/EventData/Seed.hpp
@@ -14,8 +14,9 @@
 namespace Acts {
 
 template <typename external_spacepoint_t, std::size_t N = 3ul>
-  requires(N >= 3ul)
 class Seed {
+  static_assert(N >= 3ul);
+
  public:
   using value_type = external_spacepoint_t;
   static constexpr std::size_t DIM = N;
diff --git a/Core/include/Acts/EventData/Seed.ipp b/Core/include/Acts/EventData/Seed.ipp
index 74f2c0e4169..e977a3d67d7 100644
--- a/Core/include/Acts/EventData/Seed.ipp
+++ b/Core/include/Acts/EventData/Seed.ipp
@@ -9,7 +9,6 @@
 namespace Acts {
 
 template <typename external_spacepoint_t, std::size_t N>
-  requires(N >= 3ul)
 template <typename... args_t>
   requires(sizeof...(args_t) == N) &&
           (std::same_as<external_spacepoint_t, args_t> && ...)
@@ -17,32 +16,27 @@ Seed<external_spacepoint_t, N>::Seed(const args_t&... points)
     : m_spacepoints({&points...}) {}
 
 template <typename external_spacepoint_t, std::size_t N>
-  requires(N >= 3ul)
 void Seed<external_spacepoint_t, N>::setVertexZ(float vertex) {
   m_vertexZ = vertex;
 }
 
 template <typename external_spacepoint_t, std::size_t N>
-  requires(N >= 3ul)
 void Seed<external_spacepoint_t, N>::setQuality(float seedQuality) {
   m_seedQuality = seedQuality;
 }
 
 template <typename external_spacepoint_t, std::size_t N>
-  requires(N >= 3ul)
 const std::array<const external_spacepoint_t*, N>&
 Seed<external_spacepoint_t, N>::sp() const {
   return m_spacepoints;
 }
 
 template <typename external_spacepoint_t, std::size_t N>
-  requires(N >= 3ul)
 float Seed<external_spacepoint_t, N>::z() const {
   return m_vertexZ;
 }
 
 template <typename external_spacepoint_t, std::size_t N>
-  requires(N >= 3ul)
 float Seed<external_spacepoint_t, N>::seedQuality() const {
   return m_seedQuality;
 }