Informix Error -4047: Mixed informal and formal function declaration syntax. Return type is ignored.

Reasons / Common Causes

-4047 fires when a function declaration blends informal and formal syntax — per the official guidance, the argument list gives only names (informal style, with types defined later in a VARIABLE statement), but the declaration also continues with a RETURNING clause, which is only valid in the formal (prototype) style.

1. An argument list using informal (name-only) syntax combined with a RETURNING clause, per the official guidance — the direct, only cause.

Solutions / Resolution

1. Consult the IBM Informix 4GL Reference Manual, per the official guidance, and use consistently formal or informal declaration syntax.

Examples

Mixed informal/formal syntax

FUNCTION save(id) RETURNING INTEGER
  DEFINE id INTEGER
  -- -4047: name-only argument list combined with a RETURNING clause
END FUNCTION

Corrected (formal style)

FUNCTION save(id INTEGER) RETURNING INTEGER
  ...
END FUNCTION

Diagnostic Checks

1. Check every function declaration combining a name-only argument list with a RETURNING clause, and convert it fully to formal (typed-argument) syntax.

Related Errors / Related Topics

• -4046 — "Formal declaration appeared previously for this informal function definition. The formal declaration is invalidated." A related formal/informal syntax-consistency error, about a declaration/definition mismatch rather than a single declaration blending both styles.

A function declaration mixes informal and formal syntax — use one style consistently.