core: declare the smart-pointer converting constructors once

The three constructors taking a smart pointer to a derived class carried two
copies of their template parameter list: an unqualified one under
`#ifdef __MRDOCS__`, for the reference, and the real `detail::`-qualified one.
Only MrDocs ever compiles the first, so the two could drift apart without
anything failing, and the reference would document a constraint the library
does not have.

The rules recorded in the previous commits cover this case, so state each
constraint once, with SameSmartPtr and IsPolymorphic in a defaulted template
parameter each. The rendered requires-clause is byte-for-byte what the
duplicated declarations produced.

The `#ifdef __MRDOCS__` blocks that remain remove declarations from the
reference - friends, deleted overloads, the VirtualTraits blueprint - rather
than restate them.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: jll63

CLAUDE.md

@@ -311,6 +311,12 @@ Two rules keep the reference clean; the long-form version lives next to the macr
   and substitution short-circuits at the first failure, so a dependent type in a later condition
   (`typename Other::element_type`) is only formed once the earlier ones pass.
 
+Between them these cover every constraint in the library, so **do not declare a member twice**, an
+unqualified copy under `#ifdef __MRDOCS__` beside the real one. Only MrDocs ever compiles that
+copy, so the two drift apart silently and the reference then documents a constraint the library
+does not have. The `#ifdef __MRDOCS__` blocks that remain remove declarations from the reference
+(friends, deleted overloads, the `VirtualTraits` blueprint) rather than restate them.
+
 Only expressions are affected: types are printed from the AST, so the macro may appear anywhere in
 one (`method::operator()` takes
 `typename BOOST_OPENMETHOD_UNLESS_MRDOCS(detail::) StripVirtualDecorator<Parameters>::type...` and

include/boost/openmethod/core.hpp

@@ -1227,7 +1227,7 @@ class virtual_ptr<
               detail::box_vptr<use_indirect_vptrs>(detail::null_vptr))),
           obj(std::move(other.obj)) {
     }
-#ifdef __MRDOCS__
+
     //! Construct from a (const) smart pointer to a derived class
     //!
     //! Set the object pointer with a copy of `other`. Set the v-table pointer
@@ -1252,26 +1252,19 @@ class virtual_ptr<
     //! @li @c SmartPtr must be constructible from @c const @c Other&.
     template<
         class Other,
+        typename = std::enable_if_t<BOOST_OPENMETHOD_UNLESS_MRDOCS(
+            detail::) SameSmartPtr<SmartPtr, Other, Registry>>,
         typename = std::enable_if_t<
-            SameSmartPtr<SmartPtr, Other, Registry> &&
-            IsPolymorphic<typename Other::element_type, Registry> &&
-            std::is_constructible_v<SmartPtr, const Other&>>>
-#else
-    template<
-        class Other,
-        typename = std::enable_if_t<
-            detail::SameSmartPtr<SmartPtr, Other, Registry> &&
-            detail::IsPolymorphic<typename Other::element_type, Registry> &&
+            BOOST_OPENMETHOD_UNLESS_MRDOCS(detail::)
+                IsPolymorphic<typename Other::element_type, Registry> &&
             std::is_constructible_v<SmartPtr, const Other&>>>
-#endif
     virtual_ptr(const Other& other)
         : vp(detail::box_vptr<use_indirect_vptrs>(
               other ? detail::acquire_vptr<Registry>(*other)
                     : detail::null_vptr)),
           obj(other) {
     }
 
-#if __MRDOCS__
     //! Construct from a smart pointer to a derived class
     //!
     //! Copy object pointer from `other` to `this`. Set the v-table pointer
@@ -1288,26 +1281,19 @@ class virtual_ptr<
     //! @li @c SmartPtr must be constructible from @c Other&.
     template<
         class Other,
+        typename = std::enable_if_t<BOOST_OPENMETHOD_UNLESS_MRDOCS(
+            detail::) SameSmartPtr<SmartPtr, Other, Registry>>,
         typename = std::enable_if_t<
-            SameSmartPtr<SmartPtr, Other, Registry> &&
-            IsPolymorphic<typename Other::element_type, Registry> &&
-            std::is_constructible_v<SmartPtr, Other&>>>
-#else
-    template<
-        class Other,
-        typename = std::enable_if_t<
-            detail::SameSmartPtr<SmartPtr, Other, Registry> &&
-            detail::IsPolymorphic<typename Other::element_type, Registry> &&
+            BOOST_OPENMETHOD_UNLESS_MRDOCS(detail::)
+                IsPolymorphic<typename Other::element_type, Registry> &&
             std::is_constructible_v<SmartPtr, Other&>>>
-#endif
     virtual_ptr(Other& other)
         : vp(detail::box_vptr<use_indirect_vptrs>(
               other ? detail::acquire_vptr<Registry>(*other)
                     : detail::null_vptr)),
           obj(other) {
     }
 
-#ifdef __MRDOCS__
     //! Move-construct from a smart pointer to a derived class
     //!
     //! Move object pointer from `other` to `this`. Set the v-table pointer
@@ -1331,18 +1317,12 @@ class virtual_ptr<
     //! @li @c SmartPtr must be constructible from @c Other&&.
     template<
         class Other,
+        typename = std::enable_if_t<BOOST_OPENMETHOD_UNLESS_MRDOCS(
+            detail::) SameSmartPtr<SmartPtr, Other, Registry>>,
         typename = std::enable_if_t<
-            SameSmartPtr<SmartPtr, Other, Registry> &&
-            IsPolymorphic<typename Other::element_type, Registry> &&
-            std::is_constructible_v<SmartPtr, Other&&>>>
-#else
-    template<
-        class Other,
-        typename = std::enable_if_t<
-            detail::SameSmartPtr<SmartPtr, Other, Registry> &&
-            detail::IsPolymorphic<typename Other::element_type, Registry> &&
+            BOOST_OPENMETHOD_UNLESS_MRDOCS(detail::)
+                IsPolymorphic<typename Other::element_type, Registry> &&
             std::is_constructible_v<SmartPtr, Other&&>>>
-#endif
     virtual_ptr(Other&& other)
         : vp(detail::box_vptr<use_indirect_vptrs>(
               other ? detail::acquire_vptr<Registry>(*other)