Research: Warning when type inference may fail after formatter removes explicit type

Problem

Formatters (like SwiftFormat) often simplify patterns like:

let foo: Foo = Foo()

to:

let foo = Foo()

This is problematic for Implicits when the tool cannot infer the type from Foo() because it can't build a symbol registry for certain modules:

• Third party closed source (only .swiftmodule, no source)
• Objective-C modules
• Native OS libraries (UIKit, SwiftUI, Foundation, etc.)

Proposed Solution

Add a warning when an @Implicit variable has an explicit type annotation that might be removed by formatter. Suggest using the type parameter syntax:

@Implicit(Foo.self) var foo = Foo()

This preserves type information in a way formatters won't remove.

Research Needed

• Determine if @Implicit(Type.self) syntax is currently supported
• Consider if this should be a warning or just documentation guidance

Begin by checking whether the existing @Implicit(Type.self) syntax is supported. Review how explicit type annotations are handled and how formatter changes affect inference, then decide whether the appropriate outcome is a warning or documentation guidance. Done means documenting the finding and a clear recommendation for preserving type information.