LWG4376 ABI tag in return type of [simd.mask.unary] is overconstrained

Author: burblebee

source/numerics.tex

@@ -19966,9 +19966,9 @@
 
     // \ref{simd.mask.unary}, \tcode{basic_mask} unary operators
     constexpr basic_mask operator!() const noexcept;
-    constexpr basic_vec<@\exposid{integer-from}@<Bytes>, Abi> operator+() const noexcept;
-    constexpr basic_vec<@\exposid{integer-from}@<Bytes>, Abi> operator-() const noexcept;
-    constexpr basic_vec<@\exposid{integer-from}@<Bytes>, Abi> operator~() const noexcept;
+    constexpr @\seebelow@ operator+() const noexcept;
+    constexpr @\seebelow@ operator-() const noexcept;
+    constexpr @\seebelow@ operator~() const noexcept;
 
     // \ref{simd.mask.conv}, \tcode{basic_mask} conversions
     template<class U, class A>
@@ -20179,9 +20179,9 @@
 \indexlibrarymember{operator~}{basic_mask}
 \begin{itemdecl}
 constexpr basic_mask operator!() const noexcept;
-constexpr basic_vec<@\exposid{integer-from}@<Bytes>, Abi> operator+() const noexcept;
-constexpr basic_vec<@\exposid{integer-from}@<Bytes>, Abi> operator-() const noexcept;
-constexpr basic_vec<@\exposid{integer-from}@<Bytes>, Abi> operator~() const noexcept;
+constexpr @\seebelow@ operator+() const noexcept;
+constexpr @\seebelow@ operator-() const noexcept;
+constexpr @\seebelow@ operator~() const noexcept;
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -20193,6 +20193,17 @@
 A data-parallel object where the $i^\text{th}$ element is initialized to the
 results of applying \placeholder{op} to \tcode{operator[]($i$)} for all $i$ in
 the range of \range{0}{size()}.
+
+\pnum
+\remarks
+If there exists a vectorizable signed integer type \tcode{I} such that
+\tcode{sizeof(I) == Bytes} is \tcode{true},
+\tcode{operator+}, \tcode{operator-}, and \tcode{operator~}
+return an enabled specialization \tcode{R} of \tcode{basic_vec} such that
+\tcode{R::value_type} denotes \tcode{\exposid{integer-from}<Bytes>} and
+\tcode{R::size() == size()} is \tcode{true}.
+Otherwise,
+these operators are defined as deleted and their return types are unspecified.
 \end{itemdescr}
 
 \rSec3[simd.mask.conv]{Conversions}