Fix enum errdetail to mention bytes, not chars

The enum label length is in terms of bytes, not charactes.

Author: Ian Lawrence Barwick <barwick@gmail.com>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAB8KJ=itZEJ7C9BacTHSYgeUysH4xx8wDiOnyppnSLyn6-g+Bw@mail.gmail.com

src/backend/catalog/pg_enum.c

@@ -125,7 +125,7 @@ EnumValuesCreate(Oid enumTypeOid, List *vals)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_NAME),
 					 errmsg("invalid enum label \"%s\"", lab),
-					 errdetail("Labels must be %d characters or less.",
+					 errdetail("Labels must be %d bytes or less.",
 							   NAMEDATALEN - 1)));
 
 		values[Anum_pg_enum_oid - 1] = ObjectIdGetDatum(oids[elemno]);
@@ -228,7 +228,7 @@ AddEnumLabel(Oid enumTypeOid,
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_NAME),
 				 errmsg("invalid enum label \"%s\"", newVal),
-				 errdetail("Labels must be %d characters or less.",
+				 errdetail("Labels must be %d bytes or less.",
 						   NAMEDATALEN - 1)));
 
 	/*
@@ -523,7 +523,7 @@ RenameEnumLabel(Oid enumTypeOid,
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_NAME),
 				 errmsg("invalid enum label \"%s\"", newVal),
-				 errdetail("Labels must be %d characters or less.",
+				 errdetail("Labels must be %d bytes or less.",
 						   NAMEDATALEN - 1)));
 
 	/*

src/test/regress/expected/enum.out

@@ -92,7 +92,7 @@ ORDER BY enumlabel::planets;
 ALTER TYPE planets ADD VALUE
   'plutoplutoplutoplutoplutoplutoplutoplutoplutoplutoplutoplutoplutopluto';
 ERROR:  invalid enum label "plutoplutoplutoplutoplutoplutoplutoplutoplutoplutoplutoplutoplutopluto"
-DETAIL:  Labels must be 63 characters or less.
+DETAIL:  Labels must be 63 bytes or less.
 ALTER TYPE planets ADD VALUE 'pluto' AFTER 'zeus';
 ERROR:  "zeus" is not an existing enum label
 -- if not exists tests