Can't be mutable either way

3380_extend_cnttp_2/extend-cnttp-2.md

@@ -746,11 +746,13 @@ This proposal extends class types as non-type parameters as follows. This isn't
 
 First, as with [@P2484R0], I'm referring to `to_meta_representation` as a template representation function. A class type `T` can provide an `to_meta_representation` that must be `consteval`, with one of two forms:
 
-1. It is a possibly-mutable function that returns `void`, in which case every base class and non-static data member shall have structural type and none of them shall be `mutable`.
+1. It is a possibly-mutable function that returns `void`, in which case every base class and non-static data member shall have structural type.
 2. It is a `const` function that returns some value `R` such that:
     a. `R.data()` is convertible to `std::meta::info const*`, `R.size()` is convertible to `size_t`, and `static_cast<std::meta::info const*>(R.data())[i]` shall be valid for all `0 <= i < static_cast<size_t>(R.size())`, and
     b. `T::from_meta_representation(R)` is a valid expression that yields a prvalue of type `T`.
 
+Either way, no non-static data member of `T` can be `mutable`.
+
 Second, we introduce the concept of template argument normalization and allow string literal template arguments:
 
 ::: std

3380_extend_cnttp_2/p3380r1.html

@@ -1539,8 +1539,7 @@ <h2 data-number="4.1" id="language"><span class="header-section-number">4.1</spa
 <li>It is a possibly-mutable function that returns
 <code class="sourceCode cpp"><span class="dt">void</span></code>, in
 which case every base class and non-static data member shall have
-structural type and none of them shall be
-<code class="sourceCode cpp"><span class="kw">mutable</span></code>.</li>
+structural type.</li>
 <li>It is a
 <code class="sourceCode cpp"><span class="kw">const</span></code>
 function that returns some value <code class="sourceCode cpp">R</code>
@@ -1559,6 +1558,9 @@ <h2 data-number="4.1" id="language"><span class="header-section-number">4.1</spa
 <code class="sourceCode cpp">T</code>.</li>
 </ol></li>
 </ol>
+<p>Either way, no non-static data member of
+<code class="sourceCode cpp">T</code> can be
+<code class="sourceCode cpp"><span class="kw">mutable</span></code>.</p>
 <p>Second, we introduce the concept of template argument normalization
 and allow string literal template arguments:</p>
 <div class="std">