VBC09320 — Inconsistent property accessors

Severity: Error · Family: VBC (static semantics / abstract syntax tree) · Source metadata: VBCompileErrorInfo

A module's Property Get, Property Let, and Property Set sharing a name do not together describe one valid property (MS-VBAL §5.3.1.7 Property Declarations).

This code is raised where the accessors are resolved as a group, by ScopeTreeSymbolResolver, as soon as more than one accessor exists and any of the conditions below holds. A Property Let/Set with no parameters at all is checked separately, ahead of this code: see VBC09321.

The verbose detail lists the colliding accessor declarations.

How it is raised

Situation	Example	Resolution
Two accessors' index-parameter lists differ in count, name, declared type, or `ByRef`/`ByVal` mechanism.	`Property Get Foo(i As Integer)` next to `Property Let Foo(j As Long, v As Integer)`	Give every accessor of the property identical index parameters.
An index parameter is `Optional` or a `ParamArray`, and the property has more than one accessor.	`Property Get Foo(Optional i As Integer)` next to `Property Let Foo(i As Integer, v As Integer)`	Either drop `Optional`/`ParamArray` from the index, or make the property `Get`-only.
`Property Let` and `Property Get` sharing a name declare a different value type.	`Property Get Foo() As Long` next to `Property Let Foo(v As String)`	Give the `Let` accessor's value parameter the same declared type as the `Get` accessor's return type.
`Property Set`'s value parameter is not `Object`, `Variant`, or a named class.	`Property Set Foo(v As Long)`	Type the value parameter `Object`, `Variant`, or a class.

Notes

An implicit and an explicit ByRef on a corresponding index parameter are not a difference: only the ByRef-versus-ByVal mechanism is compared, as the exception in MS-VBAL §5.3.1.7 for that case specifies.

A single accessor (a Get-only or Let-only property) has nothing to be inconsistent with, and is never reported by this code. Optional/ParamArray index parameters are legal only there.

Two corresponding parameters' declared types are compared by the symbol that declares them (Symbol.SemanticId), not by the type's bare name. A class or user-defined type named Widget in one module is not the same declared type as a different Widget declared elsewhere, even though the two share a name.

A declared type that is not resolved (not yet, or not at all) cannot be shown to mismatch anything, so it is deferred rather than flagged. Every other type-comparing static-semantics rule in RDCore follows the same convention.

The VBE bundles all of these conditions into one compile error: "Definitions of property procedures for the same property are inconsistent, or property procedure has an optional parameter, a ParamArray, or an invalid Set final parameter."

The index-parameter-equivalence and Property Set value-type conditions are literal MS-VBAL §5.3.1.7 static-semantics bullets. The Optional/ParamArray-implies-Get-only consequence is not stated in the MS-VBAL text, but the wording of the VBE compiler's error confirms it.

Table of Contents

VBC09320 — Inconsistent property accessors

How it is raised

Notes

See also