diff --git a/Eigen/src/Core/StlIterators.h b/Eigen/src/Core/StlIterators.h
index 25d457530..4576cc043 100644
--- a/Eigen/src/Core/StlIterators.h
+++ b/Eigen/src/Core/StlIterators.h
@@ -325,7 +325,7 @@ class pointer_based_stl_iterator {
  public:
   typedef Index difference_type;
   typedef typename XprType::Scalar value_type;
-#if EIGEN_CPLUSPLUS >= 202002L
+#if EIGEN_COMP_CXXVER >= 20 && defined(__cpp_lib_concepts) && __cpp_lib_concepts >= 202002L
   typedef std::conditional_t<XprType::InnerStrideAtCompileTime == 1, std::contiguous_iterator_tag,
                              std::random_access_iterator_tag>
       iterator_category;
diff --git a/Eigen/src/Core/util/Memory.h b/Eigen/src/Core/util/Memory.h
index 97cf4f3b8..0facd2690 100644
--- a/Eigen/src/Core/util/Memory.h
+++ b/Eigen/src/Core/util/Memory.h
@@ -1316,7 +1316,8 @@ inline int queryTopLevelCacheSize() {
  * This wraps C++20's std::construct_at, using placement new instead if it is not available.
  */
 
-#if EIGEN_COMP_CXXVER >= 20
+#if EIGEN_COMP_CXXVER >= 20 && defined(__cpp_lib_constexpr_dynamic_alloc) && \
+    __cpp_lib_constexpr_dynamic_alloc >= 201907L
 using std::construct_at;
 #else
 template <class T, class... Args>
diff --git a/Eigen/src/Core/util/Meta.h b/Eigen/src/Core/util/Meta.h
index 39a117e2e..40604f8ea 100644
--- a/Eigen/src/Core/util/Meta.h
+++ b/Eigen/src/Core/util/Meta.h
@@ -220,7 +220,7 @@ struct is_void : is_same<void, std::remove_const_t<T>> {};
  *
  * Post C++17: Uses std::void_t
  */
-#if EIGEN_COMP_CXXVER >= 17
+#if EIGEN_COMP_CXXVER >= 17 && defined(__cpp_lib_void_t) && __cpp_lib_void_t >= 201411L
 using std::void_t;
 #else
 template <typename...>
@@ -338,7 +338,16 @@ struct array_size<std::array<T, N>> {
  *
  * For C++20, this function just forwards to `std::ssize`, or any ADL discoverable `ssize` function.
  */
-#if EIGEN_COMP_CXXVER < 20 || EIGEN_GNUC_STRICT_LESS_THAN(10, 0, 0)
+#if EIGEN_COMP_CXXVER >= 20 && defined(__cpp_lib_ssize) && __cpp_lib_ssize >= 201902L
+
+template <typename T>
+EIGEN_CONSTEXPR auto index_list_size(T&& x) {
+  using std::ssize;
+  return ssize(std::forward<T>(x));
+}
+
+#else
+
 template <typename T>
 EIGEN_CONSTEXPR auto index_list_size(const T& x) {
   using R = std::common_type_t<std::ptrdiff_t, std::make_signed_t<decltype(x.size())>>;
@@ -349,13 +358,7 @@ template <typename T, std::ptrdiff_t N>
 EIGEN_CONSTEXPR std::ptrdiff_t index_list_size(const T (&)[N]) {
   return N;
 }
-#else
-template <typename T>
-EIGEN_CONSTEXPR auto index_list_size(T&& x) {
-  using std::ssize;
-  return ssize(std::forward<T>(x));
-}
-#endif  // EIGEN_COMP_CXXVER
+#endif
 
 /** \internal
  * Convenient struct to get the result type of a nullary, unary, binary, or
@@ -745,7 +748,7 @@ inline constexpr bool logical_xor(bool a, bool b) { return a != b; }
 inline constexpr bool check_implication(bool a, bool b) { return !a || b; }
 
 /// \internal Provide fallback for std::is_constant_evaluated for pre-C++20.
-#if EIGEN_COMP_CXXVER >= 20
+#if EIGEN_COMP_CXXVER >= 20 && defined(__cpp_lib_is_constant_evaluated) && __cpp_lib_is_constant_evaluated >= 201811L
 using std::is_constant_evaluated;
 #else
 constexpr bool is_constant_evaluated() { return false; }