Declaration expanded from macro is not visible in scope

I'm trying out declaration macros with the following minimal example:

// in module "ExampleMacro":

import SwiftCompilerPlugin
import SwiftSyntax
import SwiftSyntaxBuilder
import SwiftSyntaxMacros

public struct DefineEmptyStructMacro: DeclarationMacro {
	public static func expansion(
		of node: some FreestandingMacroExpansionSyntax,
		in context: some MacroExpansionContext
	) throws -> [DeclSyntax] {
		return ["struct Empty {}"]

struct MacroTestPlugin: CompilerPlugin {
	let providingMacros: [Macro.Type] = [
// in a different module that depends on "MacroExample":

@freestanding(declaration, names: named(Empty))
macro empty() = #externalMacro(module: "ExampleMacro", type: "DefineEmptyStructMacro")


extension Empty: Equatable {} // error: cannot find type 'Empty' in scope

It puzzles me why Empty isn't in scope. By my understanding, #empty is expanded when parsed, so at the point of the extension declaration, Empty should already be declared in the same scope. Am I using the macro wrong, or is this a bug?

1 Like