From dbf7ae6f9b8406d1a2a905b2e14c8b5bdcf569b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antonio=20S=C3=A1nchez?= <cantonios@google.com>
Date: Tue, 20 Dec 2022 18:06:03 +0000
Subject: [PATCH] Fix up C++ version detection macros and cmake tests.

---
 Eigen/src/Core/util/Macros.h |  6 +++---
 test/CMakeLists.txt          | 13 +------------
 test/constexpr.cpp           |  4 ++--
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/Eigen/src/Core/util/Macros.h b/Eigen/src/Core/util/Macros.h
index 1b0f226fe..4b8b277f2 100644
--- a/Eigen/src/Core/util/Macros.h
+++ b/Eigen/src/Core/util/Macros.h
@@ -650,11 +650,11 @@
 // The macro EIGEN_COMP_CXXVER defines the c++ version expected by the compiler.
 // For instance, if compiling with gcc and -std=c++17, then EIGEN_COMP_CXXVER
 // is defined to 17.
-#if EIGEN_CPLUSPLUS > 201703L
+#if EIGEN_CPLUSPLUS >= 202002L
   #define EIGEN_COMP_CXXVER 20
-#elif EIGEN_CPLUSPLUS > 201402L
+#elif EIGEN_CPLUSPLUS >= 201703L
   #define EIGEN_COMP_CXXVER 17
-#elif EIGEN_CPLUSPLUS > 201103L
+#elif EIGEN_CPLUSPLUS >= 201402L
   #define EIGEN_COMP_CXXVER 14
 #elif EIGEN_CPLUSPLUS >= 201103L
   #define EIGEN_COMP_CXXVER 11
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index fb7165c5d..223a9f1ae 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -185,18 +185,7 @@ ei_add_test(io)
 ei_add_test(packetmath "-DEIGEN_FAST_MATH=1")
 ei_add_test(vectorization_logic)
 ei_add_test(basicstuff)
-ei_add_test_internal(constexpr constexpr_cxx14)
-target_compile_features(constexpr_cxx14 PRIVATE cxx_std_14)
-if ("cxx_std_17" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
-  # C++17 changes some rules related to constexpr, check that it works
-  ei_add_test_internal(constexpr constexpr_cxx17)
-  target_compile_features(constexpr_cxx17 PRIVATE cxx_std_17)
-endif()
-if ("cxx_std_20" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
-  # C++20 changes some rules related to constexpr, check that it works
-  ei_add_test_internal(constexpr constexpr_cxx20)
-  target_compile_features(constexpr_cxx20 PRIVATE cxx_std_20)
-endif()
+ei_add_test(constexpr)
 ei_add_test(constructor)
 ei_add_test(linearstructure)
 ei_add_test(integer_types)
diff --git a/test/constexpr.cpp b/test/constexpr.cpp
index a327c14c4..b8f0b0920 100644
--- a/test/constexpr.cpp
+++ b/test/constexpr.cpp
@@ -15,7 +15,7 @@ EIGEN_DECLARE_TEST(constexpr) {
   // until after the constructor returns:
   // error: member ‘Eigen::internal::plain_array<int, 9, 0, 0>::array’ must be initialized by mem-initializer in
   // ‘constexpr’ constructor
-#if EIGEN_COMP_CXXVER >= 20 || defined(__clang__)
+#if EIGEN_COMP_CXXVER >= 20
   constexpr Matrix3i mat({{1, 2, 3}, {4, 5, 6}, {7, 8, 9}});
   VERIFY_IS_EQUAL(mat.size(), 9);
   VERIFY_IS_EQUAL(mat(0, 0), 1);
@@ -35,7 +35,7 @@ EIGEN_DECLARE_TEST(constexpr) {
   VERIFY_IS_EQUAL(dyn_arr(0, 0), 1);
   VERIFY_IS_EQUAL(dyn_arr.size(), 9);
   static_assert(dyn_arr.coeff(0,1) == 2);
-#endif  // EIGEN_COMP_CXXVER >= 20 || defined(__clang__)
+#endif  // EIGEN_COMP_CXXVER >= 20
 }
 
 // Check that we can use the std::initializer_list constructor for constexpr variables.