raise priority of optional and variant above sequence

Author: grisumbras

CHANGELOG.adoc

@@ -8,6 +8,7 @@ include::doc/pages/definitions.adoc[]
 == Boost 1.89.0
 
 .API Changes
+* {issue}1050[#1050] Optionals that are ranges are categorised as optionals.
 * {issue}1086[#1086] Described class support is enabled for types with bases.
 
 == Boost 1.87.0

doc/externals.hpp

@@ -212,6 +212,11 @@ struct bad_alloc {};
 /// @see https://en.cppreference.com/w/cpp/container/map
 struct map {};
 
+/// !EXTERNAL!
+///
+/// @see https://en.cppreference.com/w/cpp/container/multimap
+struct multimap {};
+
 /// !EXTERNAL!
 ///
 /// @see https://en.cppreference.com/w/cpp/container/unordered_map

doc/pages/conversion/overview.adoc

@@ -70,6 +70,20 @@ a| The result is a number equal to input and has the type
 |The result is a <<ref_string>>.
 |The result is constructed from a <<ref_string_view>>.
 
+|Type satisfying <<ref_is_variant_like>>.
+|`std::variant` and similar types, e.g. `boost::variant2::variant`.
+|The result is equal to the result of conversion of the active variant
+    alternative.
+|The result holds the first alternative for which a conversion succeeds.
+
+|Type satisfying <<ref_is_optional_like>>
+|
+|If the input value is empty, the result is a `null`. Otherwise it is
+    equivalent to conversion of the object stored inside of optional.
+|The result is default constructed if the input value is `null`. Otherwise the
+    result is constructed from the result of conversion of the input to the
+    type stored in optional.
+
 |Type satisfying <<ref_is_map_like>>.
 |A one-to-one mapping (e.g. `std::map`) with string-like keys.
 |The result is an <<ref_object>>.
@@ -99,20 +113,6 @@ a| The result is a number equal to input and has the type
 |The result is the described enumerator, corresponding to the input
     <<ref_string>>.
 
-|Type satisfying <<ref_is_variant_like>>.
-|`std::variant` and similar types, e.g. `boost::variant2::variant`.
-|The result is equal to the result of conversion of the active variant
-    alternative.
-|The result holds the first alternative for which a conversion succeeds.
-
-|Type satisfying <<ref_is_optional_like>>
-|
-|If the input value is empty, the result is a `null`. Otherwise it is
-    equivalent to conversion of the object stored inside of optional.
-|The result is default constructed if the input value is `null`. Otherwise the
-    result is constructed from the result of conversion of the input to the
-    type stored in optional.
-
 |Type satisfying <<ref_is_path_like>>.
 |`std::filesystem::path` and similar types, e.g. `boost::filesystem::path`.
 |The result is equal to the result of `path::generic_string`.

doc/pages/reference.adoc

@@ -75,24 +75,36 @@ a| *Functions* +
 <<ref_string_kind>>
 
 | *Type Traits* +
+<<ref_conversion_category_for>> +
+<<ref_described_class_category>> +
+<<ref_described_enum_category>> +
 <<ref_has_value_from>> +
 <<ref_has_value_to>> +
 <<ref_is_deallocate_trivial>> +
-<<ref_is_described_class>> +
-<<ref_is_described_enum>> +
-<<ref_is_map_like>> +
-<<ref_is_null_like>> +
-<<ref_is_optional_like>> +
-<<ref_is_path_like>> +
-<<ref_is_sequence_like>> +
-<<ref_is_string_like>> +
-<<ref_is_tuple_like>> +
-<<ref_is_variant_like>> +
+<<ref_map_category>> +
+<<ref_null_category>> +
+<<ref_optional_category>> +
+<<ref_path_category>> +
+<<ref_sequence_category>> +
+<<ref_string_category>> +
+<<ref_tuple_category>> +
+<<ref_variant_category>> +
 <<ref_result_for>> +
 <<ref_try_value_to_tag>> +
 <<ref_value_from_tag>> +
 <<ref_value_to_tag>>
 
+4+h| Deprecated
+| <<ref_is_described_class>> +
+  <<ref_is_described_enum>> +
+  <<ref_is_map_like>>
+| <<ref_is_null_like>> +
+  <<ref_is_optional_like>>
+| <<ref_is_path_like>> +
+  <<ref_is_sequence_like>> +
+  <<ref_is_string_like>>
+| <<ref_is_tuple_like>> +
+  <<ref_is_variant_like>>
 |===
 
 include::{entities-file}[leveloffset=+1]