5.2.1 Option Directives

Note

This section describes the implementation of MS-VBAL §5.2.1 Option Directives.

Directives include the Option statements (RD-VBAL §3.1 Attributes and Directives):

Directive	Description
Option Compare	Determines the comparison mode for string comparisons (§5.2.1.1).
Option Base	Determines the base (0 or 1) of implicitly-sized arrays (§5.2.1.2).
Option Explicit	Implicit declarations become compile-time errors (§5.2.1.3).
Option Private Module	Determines the accessibility of a module (§5.2.1.4).

A module's LexicalScope carries its ModuleDirectives (RD-VBAL §2.3.1.3 Name Resolution):

Member	Description
Explicit	Whether the module declares Option Explicit.
Compare	The module's Option Compare mode.
Strict	Reserved for RD-VBA's '@OptionStrict annotation. No symbol provider sets it, so it is always false, and nothing reads it.

ModuleDirectives is reachable from any scope nested under the module, via LexicalScope.EnclosingModuleDirectives().

5.2.1.1 Option Compare Directive

Note

This section describes the implementation of MS-VBAL §5.2.1.1 Option Compare Directive.

The Option Compare directive determines the comparison mode for string comparisons: Text or Binary. The comparison mode may instead be a host-defined token, which dynamically configures the comparison mode.

5.2.1.2 Option Base Directive

Note

This section describes the implementation of MS-VBAL §5.2.1.2 Option Base Directive.

The Option Base directive determines the base (0 or 1) of implicitly-sized arrays.

The lower bound of an uninitialized array value depends on the value of the Option Base directive (RD-VBAL §2.5.2.1.2 Array Values):

Option Base	Lower bound
Not specified (the default)	0
Option Base 1	1

Resolving an omitted array lower bound against Option Base is the concern of the semantic pass that materializes the array value, not of the declaration pass (RD-VBAL §2.4.1 Intrinsic Types).

5.2.1.3 Option Explicit Directive

Note

This section describes the implementation of MS-VBAL §5.2.1.3 Option Explicit Directive.

Under the Option Explicit directive, implicit declarations become compile-time errors.

Whether the enclosing module declares Option Explicit is the module-level fact a static semantics rule needs (RD-VBAL §5.0 Semantics, §5.0.1). The static-semantics layer consumes ModuleDirectives to decide what an unresolved simple name is (RD-VBAL §5.6.10 Simple Name Expressions):

Module declares Option Explicit	An unresolved simple name is
No	A deferred VBUnknownType.
Yes	A VBC09302 Variable not defined compile-time error: an Error carrying VariableNotDefined (VBCompileErrorId).

An implicit declaration by an unqualified ReDim target is legal under Option Explicit (RD-VBAL §5.4.3.3 ReDim Statement).

5.2.1.4 Option Private Directive

Note

This section describes the implementation of MS-VBAL §5.2.1.4 Option Private Directive.

The Option Private Module directive determines the accessibility of a module.

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⏮️ RD-VBAL §5.2 Module Declaration Section Structure | ⏭️ RD-VBAL §5.2.2 Implicit Definition Directives