Add type alias for event field

Author: sparr

doc/JSON/JSON_INFO.md

@@ -2160,9 +2160,11 @@ specification for it in `event.h`:
 
 <!-- {% raw %} -->
 ```cpp
+using event_field = std::pair<const char *, cata_variant_type>;
+//...
 template<>
 struct event_spec<event_type::gains_skill_level> {
-    static constexpr std::array<std::pair<const char *, cata_variant_type>, 3> fields = {{
+    static constexpr std::array<event_field, 3> fields = {{
             { "character", cata_variant_type::character_id },
             { "skill", cata_variant_type::skill_id },
             { "new_level", cata_variant_type::int_ },

src/event.cpp

@@ -139,8 +139,7 @@ namespace event_detail
 {
 
 #define DEFINE_EVENT_HELPER_FIELDS(type) \
-    constexpr std::array<std::pair<const char *, cata_variant_type>, \
-    type::fields.size()> type::fields;
+    constexpr std::array<event_field, type::fields.size()> type::fields;
 
 DEFINE_EVENT_HELPER_FIELDS( event_spec_empty )
 DEFINE_EVENT_HELPER_FIELDS( event_spec_character )
@@ -152,7 +151,7 @@ static_assert( static_cast<int>( event_type::num_event_types ) == 107,
                "its fields definition then you probably don't need a definition here." );
 
 #define DEFINE_EVENT_FIELDS(type) \
-    constexpr std::array<std::pair<const char *, cata_variant_type>, \
+    constexpr std::array<event_field, \
     event_spec<event_type::type>::fields.size()> \
     event_spec<event_type::type>::fields;