[simd.permute.*] Change M back to V since the wording refers to V

This was changed editorially by b6e5010
as part of "2025-06 LWG Motion 13: P3691R1 Reconsider naming of the
namespace for std::simd", but turned out not to be a helpful change,
because it makes other wording more complex.

Fixes NB US 180-295 (C++26 CD).

Author: mattkretz

source/numerics.tex

@@ -16968,33 +16968,33 @@
 
   template<@\exposid{simd-size-type}@ N = @\seebelow@, @\exposconcept{simd-vec-type}@ V, class IdxMap>
     constexpr resize_t<N, V> permute(const V& v, IdxMap&& idxmap);
-  template<@\exposid{simd-size-type}@ N = @\seebelow@, @\exposconcept{simd-mask-type}@ M, class IdxMap>
-    constexpr resize_t<N, M> permute(const M& v, IdxMap&& idxmap);
+  template<@\exposid{simd-size-type}@ N = @\seebelow@, @\exposconcept{simd-mask-type}@ V, class IdxMap>
+    constexpr resize_t<N, V> permute(const V& v, IdxMap&& idxmap);
 
   // \ref{simd.permute.dynamic}, dynamic permute
   template<@\exposconcept{simd-vec-type}@ V, @\exposconcept{simd-integral}@ I>
     constexpr resize_t<I::size(), V> permute(const V& v, const I& indices);
-  template<@\exposconcept{simd-mask-type}@ M, @\exposconcept{simd-integral}@ I>
-    constexpr resize_t<I::size(), M> permute(const M& v, const I& indices);
+  template<@\exposconcept{simd-mask-type}@ V, @\exposconcept{simd-integral}@ I>
+    constexpr resize_t<I::size(), V> permute(const V& v, const I& indices);
 
   // \ref{simd.permute.mask}, mask permute
   template<@\exposconcept{simd-vec-type}@ V>
     constexpr V compress(const V& v, const typename V::mask_type& selector);
-  template<@\exposconcept{simd-mask-type}@ M>
-    constexpr M compress(const M& v, const type_identity_t<M>& selector);
+  template<@\exposconcept{simd-mask-type}@ V>
+    constexpr V compress(const V& v, const type_identity_t<V>& selector);
   template<@\exposconcept{simd-vec-type}@ V>
     constexpr V compress(const V& v, const typename V::mask_type& selector,
                          const typename V::value_type& fill_value);
-  template<@\exposconcept{simd-mask-type}@ M>
-    constexpr M compress(const M& v, const type_identity_t<M>& selector,
+  template<@\exposconcept{simd-mask-type}@ V>
+    constexpr V compress(const V& v, const type_identity_t<V>& selector,
                          const typename M::value_type& fill_value);
 
   template<@\exposconcept{simd-vec-type}@ V>
     constexpr V expand(const V& v, const typename V::mask_type& selector,
                        const V& original = {});
-  template<@\exposconcept{simd-mask-type}@ M>
-    constexpr M expand(const M& v, const type_identity_t<M>& selector,
-                       const M& original = {});
+  template<@\exposconcept{simd-mask-type}@ V>
+    constexpr V expand(const V& v, const type_identity_t<V>& selector,
+                       const V& original = {});
 
   // \ref{simd.permute.memory}, memory permute
   template<class V = @\seebelow@, ranges::@\libconcept{contiguous_range}@ R, @\exposconcept{simd-integral}@ I, class... Flags>
@@ -19102,8 +19102,8 @@
 \begin{itemdecl}
 template<@\exposid{simd-size-type}@ N = @\seebelow@, @\exposconcept{simd-vec-type}@ V, class IdxMap>
   constexpr resize_t<N, V> permute(const V& v, IdxMap&& idxmap);
-template<@\exposid{simd-size-type}@ N = @\seebelow@, @\exposconcept{simd-mask-type}@ M, class IdxMap>
-  constexpr resize_t<N, M> permute(const M& v, IdxMap&& idxmap);
+template<@\exposid{simd-size-type}@ N = @\seebelow@, @\exposconcept{simd-mask-type}@ V, class IdxMap>
+  constexpr resize_t<N, V> permute(const V& v, IdxMap&& idxmap);
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -19161,8 +19161,8 @@
 \begin{itemdecl}
 template<@\exposconcept{simd-vec-type}@ V, @\exposconcept{simd-integral}@ I>
   constexpr resize_t<I::size(), V> permute(const V& v, const I& indices);
-template<@\exposconcept{simd-mask-type}@ M, @\exposconcept{simd-integral}@ I>
-  constexpr resize_t<I::size(), M> permute(const M& v, const I& indices);
+template<@\exposconcept{simd-mask-type}@ V, @\exposconcept{simd-integral}@ I>
+  constexpr resize_t<I::size(), V> permute(const V& v, const I& indices);
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -19183,8 +19183,8 @@
 \begin{itemdecl}
 template<@\exposconcept{simd-vec-type}@ V>
   constexpr V compress(const V& v, const typename V::mask_type& selector);
-template<@\exposconcept{simd-mask-type}@ M>
-  constexpr M compress(const M& v, const type_identity_t<M>& selector);
+template<@\exposconcept{simd-mask-type}@ V>
+  constexpr V compress(const V& v, const type_identity_t<V>& selector);
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -19216,8 +19216,8 @@
 template<@\exposconcept{simd-vec-type}@ V>
   constexpr V compress(const V& v, const typename V::mask_type& selector,
                        const typename V::value_type& fill_value);
-template<@\exposconcept{simd-mask-type}@ M>
-  constexpr M compress(const M& v, const type_identity_t<M>& selector,
+template<@\exposconcept{simd-mask-type}@ V>
+  constexpr V compress(const V& v, const type_identity_t<V>& selector,
                        const typename M::value_type& fill_value);
 \end{itemdecl}
 
@@ -19245,8 +19245,8 @@
 \begin{itemdecl}
 template<@\exposconcept{simd-vec-type}@ V>
   constexpr V expand(const V& v, const typename V::mask_type& selector, const V& original = {});
-template<@\exposconcept{simd-mask-type}@ M>
-  constexpr M expand(const M& v, const type_identity_t<M>& selector, const M& original = {});
+template<@\exposconcept{simd-mask-type}@ V>
+  constexpr V expand(const V& v, const type_identity_t<V>& selector, const V& original = {});
 \end{itemdecl}
 
 \begin{itemdescr}