Function getBaseType

src/backend/utils/cache/lsyscache.c:3121–3127

* getBaseType * If the given type is a domain, return its base type; * otherwise return the type's own OID. */

 *		otherwise return the type's own OID.
 */
Oid
getBaseType(Oid typid)
{
	int32		typmod = -1;

	return getBaseTypeAndTypmod(typid, &typmod);
}

/*
 * getBaseTypeAndTypmod