patch 8.1.1838: there is :spellwrong and :spellgood but not :spellrare
Problem: There is :spellwrong and :spellgood but not :spellrare.
Solution: Add :spellrare. (Martin Tournoij, closes #4291)
diff --git a/src/spell.h b/src/spell.h
index 085f18c..380e5ec 100644
--- a/src/spell.h
+++ b/src/spell.h
@@ -298,4 +298,8 @@
SPELL_EXTERN spelltab_T spelltab;
SPELL_EXTERN int did_set_spelltab;
+// Values for "what" argument of spell_add_word()
+#define SPELL_ADD_GOOD 0
+#define SPELL_ADD_BAD 1
+#define SPELL_ADD_RARE 2
#endif