Revert to C++20

CMakeLists.txt

@@ -110,6 +110,9 @@ find_package(spdlog CONFIG REQUIRED)
 # https://github.com/intel/tbb
 find_package(TBB CONFIG REQUIRED)
 
+# https://github.com/TartanLlama/expected
+find_package(tl-expected CONFIG REQUIRED)
+
 # https://github.com/TartanLlama/function_ref
 find_package(tl-function-ref CONFIG REQUIRED)
 

include/Apply_move.hpp

@@ -13,9 +13,9 @@
 
 #include <spdlog/spdlog.h>
 
-#include <expected>
 #include <functional>
 #include <string>
+#include <tl/expected.hpp>
 #include <tl/function_ref.hpp>
 
 /// @brief An applicative function similar to std::apply, but on manifolds
@@ -28,7 +28,7 @@
 /// @see https://tl.tartanllama.xyz/en/latest/api/function_ref.html
 /// @see https://tl.tartanllama.xyz/en/latest/api/expected.html
 template <typename ManifoldType,
-          typename ExpectedType = std::expected<ManifoldType, std::string>,
+          typename ExpectedType = tl::expected<ManifoldType, std::string>,
           typename FunctionType = tl::function_ref<ExpectedType(ManifoldType&)>>
 auto constexpr apply_move(ManifoldType&& t_manifold,
                           FunctionType   t_move) noexcept -> decltype(auto)

include/Ergodic_moves_3.hpp

@@ -14,15 +14,15 @@
 #ifndef CDT_PLUSPLUS_ERGODIC_MOVES_3_HPP
 #define CDT_PLUSPLUS_ERGODIC_MOVES_3_HPP
 
-#include <expected>
+#include <tl/expected.hpp>
 
 #include "Manifold.hpp"
 #include "Move_tracker.hpp"
 
 namespace ergodic_moves
 {
   using Manifold         = manifolds::Manifold_3;
-  using Expected         = std::expected<Manifold, std::string>;
+  using Expected         = tl::expected<Manifold, std::string>;
   using Cell_handle      = Cell_handle_t<3>;
   using Cell_container   = std::vector<Cell_handle>;
   using Edge_handle      = Edge_handle_t<3>;
@@ -101,7 +101,7 @@ namespace ergodic_moves
     // We've run out of (2,2) cells
     std::string const msg = "No (2,3) move possible.\n";
     spdlog::warn(msg);
-    return std::unexpected(msg);
+    return tl::unexpected(msg);
   }
 
   /// @brief Perform a TriangulationDataStructure_3::flip on an edge
@@ -143,7 +143,7 @@ namespace ergodic_moves
     // We've run out of edges to try
     std::string const msg = "No (3,2) move possible.\n";
     spdlog::warn(msg);
-    return std::unexpected(msg);
+    return tl::unexpected(msg);
   }  // do_32_move()
 
   /// @brief Find a (2,6) move location
@@ -211,7 +211,7 @@ namespace ergodic_moves
 #ifndef NDEBUG
           spdlog::trace(msg);
 #endif
-          return std::unexpected(msg);
+          return tl::unexpected(msg);
         }
 
         // Get indices of vertices of common face with respect to bottom cell
@@ -236,7 +236,7 @@ namespace ergodic_moves
 #ifndef NDEBUG
           spdlog::trace(msg);
 #endif
-          return std::unexpected(msg);
+          return tl::unexpected(msg);
         }
 
         // Do the (2,6) move
@@ -257,7 +257,7 @@ namespace ergodic_moves
 #ifndef NDEBUG
           spdlog::trace(msg);
 #endif
-          return std::unexpected(msg);
+          return tl::unexpected(msg);
         }
 
         // Each incident cell should be combinatorially and geometrically valid
@@ -275,7 +275,7 @@ namespace ergodic_moves
 #ifndef NDEBUG
           spdlog::trace(msg);
 #endif
-          return std::unexpected(msg);
+          return tl::unexpected(msg);
         }
 
         // Now assign a geometric point to the center vertex
@@ -311,7 +311,7 @@ namespace ergodic_moves
 #ifndef NDEBUG
           spdlog::trace(msg);
 #endif
-          return std::unexpected(msg);
+          return tl::unexpected(msg);
         }
 
         return t_manifold;
@@ -324,7 +324,7 @@ namespace ergodic_moves
     // We've run out of (1,3) simplices to try
     std::string const msg = "No (2,6) move possible.\n";
     spdlog::warn(msg);
-    return std::unexpected(msg);
+    return tl::unexpected(msg);
   }  // do_26_move()
 
   /// @brief Find a (6,2) move location
@@ -478,7 +478,7 @@ namespace ergodic_moves
     // We've run out of vertices to try
     std::string const msg = "No (6,2) move possible.\n";
     spdlog::warn(msg);
-    return std::unexpected(msg);
+    return tl::unexpected(msg);
   }  // do_62_move()
 
   /// @brief Find all cells incident to the edge
@@ -834,7 +834,7 @@ namespace ergodic_moves
     // We've run out of edges to try
     std::string const msg = "No (4,4) move possible.\n";
     spdlog::warn(msg);
-    return std::unexpected(msg);
+    return tl::unexpected(msg);
   }  // do_44_move()
 
   /// @brief Check move correctness

include/Move_command.hpp

@@ -15,7 +15,7 @@
 #include "Ergodic_moves_3.hpp"
 
 template <typename ManifoldType,
-          typename ExpectedType = std::expected<ManifoldType, std::string>,
+          typename ExpectedType = tl::expected<ManifoldType, std::string>,
           typename FunctionType = tl::function_ref<ExpectedType(ManifoldType&)>>
 class MoveCommand
 {

tests/Function_ref_test.cpp

@@ -87,7 +87,7 @@ SCENARIO("Function_ref operations" * doctest::test_suite("function_ref"))
     auto constexpr desired_timeslices = 4;
     Manifold_3 manifold(desired_simplices, desired_timeslices);
     REQUIRE(manifold.is_correct());
-    tl::function_ref<std::expected<Manifold_3, std::string>(Manifold_3&)> const
+    tl::function_ref<tl::expected<Manifold_3, std::string>(Manifold_3&)> const
         complex_ref(ergodic_moves::do_23_move);
     WHEN("The function_ref is invoked.")
     {

vcpkg.json

@@ -11,6 +11,7 @@
     "pcg",
     "spdlog",
     "tbb",
+    "tl-expected",
     "tl-function-ref",
     {
       "name": "yasm-tool",