Function find_typmod_coercion_function

src/backend/parser/parse_coerce.c:3303–3344

* find_typmod_coercion_function -- does the given type need length coercion? * * If the target type possesses a pg_cast function from itself to itself, * it must need length coercion. * * "bpchar" (ie, char(N)) and "numeric" are examples of such types. * * If the given type is a varlena array type, we do not look for a coercion * function associated directly with the array type, but instea

 *	COERCION_PATH_ARRAYCOERCE: apply the function using ArrayCoerceExpr
 */
CoercionPathType
find_typmod_coercion_function(Oid typeId,
							  Oid *funcid)
{
	CoercionPathType result;
	Type		targetType;
	Form_pg_type typeForm;
	HeapTuple	tuple;

	*funcid = InvalidOid;
	result = COERCION_PATH_FUNC;

	targetType = typeidType(typeId);
	typeForm = (Form_pg_type) GETSTRUCT(targetType);

	/* Check for a "true" array type */
	if (IsTrueArrayType(typeForm))
	{
		/* Yes, switch our attention to the element type */
		typeId = typeForm->typelem;
		result = COERCION_PATH_ARRAYCOERCE;
	}
	ReleaseSysCache(targetType);

	/* Look in pg_cast */
	tuple = SearchSysCache2(CASTSOURCETARGET,
							ObjectIdGetDatum(typeId),
							ObjectIdGetDatum(typeId));

	if (HeapTupleIsValid(tuple))
	{
		Form_pg_cast castForm = (Form_pg_cast) GETSTRUCT(tuple);

		*funcid = castForm->castfunc;
		ReleaseSysCache(tuple);
	}

	if (!OidIsValid(*funcid))
		result = COERCION_PATH_NONE;

	return result;
}

/*
 * is_complex_array