From 101c534dff395c8fa403fff01043e6ca17768d4b Mon Sep 17 00:00:00 2001
From: serge-sans-paille <sergesanspaille@free.fr>
Date: Sun, 12 Oct 2025 11:20:17 +0200
Subject: [PATCH 1/2] Make xsimd_scalar.hpp independent from xsimd::batch

This paves the way for cleaner error when trying to instantiate an
xsimd::batch when to architecture is available.

Related to #1143
---
 include/xsimd/arch/xsimd_scalar.hpp | 21 +--------------------
 1 file changed, 1 insertion(+), 20 deletions(-)

diff --git a/include/xsimd/arch/xsimd_scalar.hpp b/include/xsimd/arch/xsimd_scalar.hpp
index 2452d9e9c..1e309f149 100644
--- a/include/xsimd/arch/xsimd_scalar.hpp
+++ b/include/xsimd/arch/xsimd_scalar.hpp
@@ -32,11 +32,6 @@
 
 namespace xsimd
 {
-    template <class T, class A>
-    class batch;
-    template <class T, class A>
-    class batch_bool;
-
     using std::abs;
 
     using std::acos;
@@ -779,20 +774,6 @@ namespace xsimd
 
     namespace detail
     {
-        template <class T>
-        struct value_type_or_type_helper
-        {
-            using type = T;
-        };
-        template <class T, class A>
-        struct value_type_or_type_helper<batch<T, A>>
-        {
-            using type = T;
-        };
-
-        template <class T>
-        using value_type_or_type = typename value_type_or_type_helper<T>::type;
-
         template <class T0, class T1>
         XSIMD_INLINE typename std::enable_if<std::is_integral<T1>::value, T0>::type
         ipow(const T0& x, const T1& n) noexcept
@@ -801,7 +782,7 @@ namespace xsimd
             T0 a = x;
             T1 b = n;
             bool const recip = b < 0;
-            T0 r(static_cast<value_type_or_type<T0>>(1));
+            T0 r(static_cast<T0>(1));
             while (1)
             {
                 if (b & 1)

From 74d315eef7d72ba78a3b567baba1a2d601f97262 Mon Sep 17 00:00:00 2001
From: serge-sans-paille <sergesanspaille@free.fr>
Date: Sun, 12 Oct 2025 22:36:28 +0200
Subject: [PATCH 2/2] Proper static_assert when trying to instantiate a batch
 while no arch is supported

Fix #1143
---
 include/xsimd/xsimd.hpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/xsimd/xsimd.hpp b/include/xsimd/xsimd.hpp
index 1ae9f5867..e50dc3bd1 100644
--- a/include/xsimd/xsimd.hpp
+++ b/include/xsimd/xsimd.hpp
@@ -63,7 +63,16 @@
 #include "memory/xsimd_aligned_allocator.hpp"
 
 #if defined(XSIMD_NO_SUPPORTED_ARCHITECTURE)
-// to type definition or anything appart from scalar definition and aligned allocator
+// no type definition or anything apart from scalar definition and aligned allocator
+namespace xsimd
+{
+    template <class T, class A = void>
+    class batch
+    {
+        static constexpr bool supported_architecture = sizeof(A*) == 0; // type-dependant but always false
+        static_assert(supported_architecture, "No SIMD architecture detected, cannot instantiate a batch");
+    };
+}
 #else
 #include "types/xsimd_batch.hpp"
 #include "types/xsimd_batch_constant.hpp"