Informix Error -4491

Reasons / Common Causes

-4491 fires when more than one copy of a function prototype appears in scope, and one of them names a formal parameter differently than the others — per the official guidance, all prototype copies for the same function must agree on parameter names.

1. Multiple function prototype copies disagreeing on a formal parameter's name, per the official guidance — the direct, only cause.

Solutions / Resolution

1. Make all prototype copies use the same parameter name.

Examples

Disagreeing parameter names across prototype copies

FUNCTION save(order_id INTEGER) RETURNING INTEGER
...
FUNCTION save(id INTEGER) RETURNING INTEGER
-- -4491: the parameter is named "order_id" in one copy, "id" in the other

Corrected

FUNCTION save(order_id INTEGER) RETURNING INTEGER

Diagnostic Checks

1. Check every prototype copy of the function, and make their parameter names consistent.

Related Errors / Related Topics

• -4053 — "Function "name" has already been declared with a different prototype." A related function-redeclaration error, about the argument count/type disagreeing rather than just the parameter's name.
• -4492 — "Warning: The parameter is assigned a new default value." A related prototype-consistency warning, about disagreeing default values rather than parameter names.

Multiple prototype copies of a function disagree on a parameter's name — make them consistent.