From 431a18bdb740b45937fd16c754a2d2cdfb53fbd3 Mon Sep 17 00:00:00 2001
From: Richard Barnes <rbarnes@umn.edu>
Date: Mon, 15 Sep 2025 10:36:54 -0700
Subject: [PATCH] Remove deprecated constexpr definitions

---
 include/xtensor/containers/xfixed.hpp   | 30 -------------------------
 include/xtensor/containers/xstorage.hpp |  5 -----
 include/xtensor/core/xfunction.hpp      | 12 ----------
 3 files changed, 47 deletions(-)

diff --git a/include/xtensor/containers/xfixed.hpp b/include/xtensor/containers/xfixed.hpp
index 4ab3a75c3..6ac029881 100644
--- a/include/xtensor/containers/xfixed.hpp
+++ b/include/xtensor/containers/xfixed.hpp
@@ -381,21 +381,6 @@ namespace xt
         friend class xcontainer<xfixed_container<ET, S, L, SH, Tag>>;
     };
 
-#ifdef XTENSOR_HAS_CONSTEXPR_ENHANCED
-    // Out of line definitions to prevent linker errors prior to C++17
-    template <class ET, class S, layout_type L, bool SH, class Tag>
-    constexpr
-        typename xfixed_container<ET, S, L, SH, Tag>::inner_shape_type xfixed_container<ET, S, L, SH, Tag>::m_shape;
-
-    template <class ET, class S, layout_type L, bool SH, class Tag>
-    constexpr
-        typename xfixed_container<ET, S, L, SH, Tag>::inner_strides_type xfixed_container<ET, S, L, SH, Tag>::m_strides;
-
-    template <class ET, class S, layout_type L, bool SH, class Tag>
-    constexpr typename xfixed_container<ET, S, L, SH, Tag>::inner_backstrides_type
-        xfixed_container<ET, S, L, SH, Tag>::m_backstrides;
-#endif
-
     /****************************************
      * xfixed_container_adaptor declaration *
      ****************************************/
@@ -518,21 +503,6 @@ namespace xt
         friend class xcontainer<xfixed_adaptor<EC, S, L, SH, Tag>>;
     };
 
-#ifdef XTENSOR_HAS_CONSTEXPR_ENHANCED
-    // Out of line definitions to prevent linker errors prior to C++17
-    template <class EC, class S, layout_type L, bool SH, class Tag>
-    constexpr
-        typename xfixed_adaptor<EC, S, L, SH, Tag>::inner_shape_type xfixed_adaptor<EC, S, L, SH, Tag>::m_shape;
-
-    template <class EC, class S, layout_type L, bool SH, class Tag>
-    constexpr
-        typename xfixed_adaptor<EC, S, L, SH, Tag>::inner_strides_type xfixed_adaptor<EC, S, L, SH, Tag>::m_strides;
-
-    template <class EC, class S, layout_type L, bool SH, class Tag>
-    constexpr typename xfixed_adaptor<EC, S, L, SH, Tag>::inner_backstrides_type
-        xfixed_adaptor<EC, S, L, SH, Tag>::m_backstrides;
-#endif
-
     /************************************
      * xfixed_container implementation *
      ************************************/
diff --git a/include/xtensor/containers/xstorage.hpp b/include/xtensor/containers/xstorage.hpp
index 28ad238e5..811ab80b7 100644
--- a/include/xtensor/containers/xstorage.hpp
+++ b/include/xtensor/containers/xstorage.hpp
@@ -1731,11 +1731,6 @@ namespace xt
         XTENSOR_CONSTEXPR_ENHANCED_STATIC cast_type m_array = cast_type({X...});
     };
 
-#ifdef XTENSOR_HAS_CONSTEXPR_ENHANCED
-    template <std::size_t... X>
-    constexpr typename fixed_shape<X...>::cast_type fixed_shape<X...>::m_array;
-#endif
-
 #undef XTENSOR_FIXED_SHAPE_CONSTEXPR
 
     template <class E, std::ptrdiff_t Start, std::ptrdiff_t End = -1>
diff --git a/include/xtensor/core/xfunction.hpp b/include/xtensor/core/xfunction.hpp
index 65ee5050e..8f85892fb 100644
--- a/include/xtensor/core/xfunction.hpp
+++ b/include/xtensor/core/xfunction.hpp
@@ -67,18 +67,6 @@ namespace xt
             XTENSOR_CONSTEXPR_ENHANCED_STATIC bool is_initialized = true;
         };
 
-#ifdef XTENSOR_HAS_CONSTEXPR_ENHANCED
-        // Out of line definitions to prevent linker errors prior to C++17
-        template <std::size_t... N, class is_shape_trivial>
-        constexpr fixed_shape<N...> xfunction_cache_impl<fixed_shape<N...>, is_shape_trivial>::shape;
-
-        template <std::size_t... N, class is_shape_trivial>
-        constexpr bool xfunction_cache_impl<fixed_shape<N...>, is_shape_trivial>::is_trivial;
-
-        template <std::size_t... N, class is_shape_trivial>
-        constexpr bool xfunction_cache_impl<fixed_shape<N...>, is_shape_trivial>::is_initialized;
-#endif
-
         template <class... CT>
         struct xfunction_bool_load_type
         {