swift

80d949ec - Diagnose inout uses of 'lets' in constructors in the type checker.

Diagnose inout uses of 'lets' in constructors in the type checker. Stored `let` properties of a struct, class, or actor permit 'inout' modification within the constructor body after they have been initialized. Tentatively remove this rule, only allowing such `let` properties to be initialized (assigned to) and not treated as `inout`. Fixes rdar://127258363.