From 5dcb650651a9a65c9dd7249f9ad383e8565be657 Mon Sep 17 00:00:00 2001
From: Tom Scogland <scogland1@llnl.gov>
Date: Thu, 9 Dec 2021 17:44:49 +0000
Subject: [PATCH 1/2] first cut requiring c++17

Only used a bit of basic c++17 to pull some of the crud out of tuple.
Now uses overload resolution for get rather than template instantiation.
---
 .gitignore             |  8 ++++++--
 CMakeLists.txt         | 11 +++++------
 include/camp/tuple.hpp | 25 ++++++++++++++-----------
 3 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/.gitignore b/.gitignore
index a9427bd9..047c4574 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,9 +10,13 @@
 .vscode/
 .cache/
 
+# codespaces clean
+.venv/
+
 # build directories
-build/
-build-*/
+/build/
+/build-*/
+/*-build/
 cmake-build-*/
 docker-*-build/
 /Debug/
diff --git a/CMakeLists.txt b/CMakeLists.txt
index a640eeaa..842ed9a6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,19 +4,18 @@ project (camp
   LANGUAGES CXX C
   VERSION 0.1.0)
 
-# Default to C++11 if not set so GTest/GMock can build
+# Default to C++17 if not set so GTest/GMock can build
 if (NOT BLT_CXX_STD)
-    set(BLT_CXX_STD "c++14" CACHE STRING "")
+    set(BLT_CXX_STD "c++17" CACHE STRING "")
 else()
-    set(_unsupported_cxx "c++98" "c++11")
+    set(_unsupported_cxx "c++98" "c++11" "c++14")
     if (BLT_CXX_STD IN_LIST _unsupported_cxx)
-      message(FATAL_ERROR "CAMP and the RAJA framework no longer support c++11, select a c++ standard of 14 or higher")
+      message(FATAL_ERROR "CAMP and the RAJA framework no longer support c++ standards below c++17, select a c++ standard of 14 or higher")
     endif()
 endif()
 
 include(cmake/load_blt.cmake)
 
-
 cmake_dependent_option(CAMP_ENABLE_TESTS "Build tests" On "ENABLE_TESTS" Off)
 
 # if ENABLE_TESTS is defined by a parent project, and
@@ -112,7 +111,7 @@ target_include_directories (camp INTERFACE
   )
 set_target_properties (camp PROPERTIES
   INTERFACE_LIB_VERSION $camp_VERSION
-  INTERFACE_COMPILE_FEATURES cxx_std_14)
+  INTERFACE_COMPILE_FEATURES cxx_std_17)
 
 include(CMakePackageConfigHelpers)
 
diff --git a/include/camp/tuple.hpp b/include/camp/tuple.hpp
index e0fed385..0ccb5d20 100644
--- a/include/camp/tuple.hpp
+++ b/include/camp/tuple.hpp
@@ -106,12 +106,15 @@ namespace internal
     {
     }
 
-    CAMP_HOST_DEVICE constexpr const Type& get_inner() const noexcept
+    CAMP_HOST_DEVICE constexpr auto& get_inner(::camp::num<index>) const noexcept
     {
       return val;
     }
 
-    CAMP_HOST_DEVICE constexpr Type& get_inner() noexcept { return val; }
+    CAMP_HOST_DEVICE constexpr auto& get_inner(::camp::num<index>) noexcept
+    {
+      return val;
+    }
 
   public:
     Type val;
@@ -130,12 +133,12 @@ namespace internal
     {
     }
 
-    CAMP_HOST_DEVICE constexpr const Type& get_inner() const noexcept
+    CAMP_HOST_DEVICE constexpr const Type& get_inner(::camp::num<index>) const noexcept
     {
       return ((Type const*)this)[0];
     }
 
-    CAMP_HOST_DEVICE constexpr Type& get_inner() noexcept
+    CAMP_HOST_DEVICE constexpr Type& get_inner(::camp::num<index>) noexcept
     {
       return ((Type*)this)[0];
     }
@@ -151,7 +154,7 @@ CAMP_HOST_DEVICE constexpr auto& get(const Tuple& t) noexcept
 {
   using internal::tpl_get_store;
   static_assert(tuple_size<Tuple>::value > index, "index out of range");
-  return static_cast<tpl_get_store<Tuple, index> const&>(t.base).get_inner();
+  return t.base.get_inner(num<index>{});
 }
 
 template <camp::idx_t index, class Tuple>
@@ -159,7 +162,7 @@ CAMP_HOST_DEVICE constexpr auto& get(Tuple& t) noexcept
 {
   using internal::tpl_get_store;
   static_assert(tuple_size<Tuple>::value > index, "index out of range");
-  return static_cast<tpl_get_store<Tuple, index>&>(t.base).get_inner();
+  return t.base.get_inner(num<index>{});
 }
 
 // by type
@@ -171,8 +174,7 @@ CAMP_HOST_DEVICE constexpr auto& get(const Tuple& t) noexcept
   static_assert(!std::is_same<camp::nil, index_type>::value,
                 "invalid type index");
 
-  return static_cast<tpl_get_store<Tuple, index_type::value>&>(t.base)
-      .get_inner();
+  return t.base.get_inner(index_type{});
 }
 
 template <typename T, class Tuple>
@@ -183,8 +185,7 @@ CAMP_HOST_DEVICE constexpr auto& get(Tuple& t) noexcept
   static_assert(!std::is_same<camp::nil, index_type>::value,
                 "invalid type index");
 
-  return static_cast<tpl_get_store<Tuple, index_type::value>&>(t.base)
-      .get_inner();
+  return t.base.get_inner(index_type{});
 }
 
 namespace internal
@@ -228,10 +229,12 @@ namespace internal
     template <typename RTuple>
     CAMP_HOST_DEVICE tuple_helper& operator=(const RTuple& rhs)
     {
-      return (camp::sink((this->tuple_storage<Indices, Types>::get_inner() =
+      return (camp::sink((this->get_inner(num<Indices>{}) =
                               ::camp::get<Indices>(rhs))...),
               *this);
     }
+    
+    using internal::tuple_storage<Indices, Types>::get_inner...;
   };
 
   template <typename Types, typename Indices>

From 6e4d2f8580e5a11498a38eb61055c80d090bb6b4 Mon Sep 17 00:00:00 2001
From: Tom Scogland <scogland1@llnl.gov>
Date: Thu, 9 Dec 2021 16:28:53 -0800
Subject: [PATCH 2/2] Update CMakeLists.txt

Co-authored-by: Rich Hornung <hornung1@llnl.gov>
---
 CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 842ed9a6..219ac02c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,7 @@ if (NOT BLT_CXX_STD)
 else()
     set(_unsupported_cxx "c++98" "c++11" "c++14")
     if (BLT_CXX_STD IN_LIST _unsupported_cxx)
-      message(FATAL_ERROR "CAMP and the RAJA framework no longer support c++ standards below c++17, select a c++ standard of 14 or higher")
+      message(FATAL_ERROR "CAMP and the RAJA framework no longer support c++ standards below c++17, select a c++ standard of 17 or higher")
     endif()
 endif()