Why does Array.contains cause a compile-time error when comparing an optional value with a non-optional value in Swift?

I’m working with Swift and ran into an issue when using the contains(_:) method on an array. The following code works fine:

let result = ["hello", "world"].contains(Optional("hello")) // ✅ Works fine

But when I try to use the same contains method with the array declared in a separate variable, I get a compile-time error:

let stringArray = ["hello", "world"]
let result = stringArray.contains(Optional("hello")) // ❌ Compile-time error

Both examples seem conceptually similar, but the second one causes a compile-time error, while the first one works fine.

I understand that when comparing an optional value (Optional("hello")) with a non-optional value ("hello"), Swift automatically promotes the non-optional value to an optional (i.e., "hello" becomes Optional("hello")). 🔗 reference

What I don’t understand is why the first code works but the second one doesn’t, even though both cases involve comparing an optional value with a non-optional value. I know that there are different ways to resolve this, like using nil coalescing or optional binding, but what I’m really looking for is a detailed explanation of why this issue occurs at the compile-time level.

Can anyone explain the underlying reason for this behavior?