Anonymous property not allowed to have `some` type

[AnthonyLatsis]

Describe the bug

let _: some Equatable = true // error: 'some' type can only be declared on a single property declaration

Expected behavior
The described limitation need not apply to an irrefutable pattern, since there is no harm in regarding it as a single declaration.

Environment
Swift version 5.8-dev (Swift d124b35)

I am pretty confident this is an adequate candidate for a first-time issue, but I have not run any tests against the small correction this seems to require.

[slavapestov]

I'm not sure this is really a bug. There's no property being declared here, the expression is just evaluated for its side effect. What purpose would an opaque result type have here?

[AnthonyLatsis]

I won’t go as far as calling it a bug either, but I don’t see the point in having this exception, unless we have to break sweat to it work.

[slavapestov]

I think it can be justified as follows: some P declares an opaque return type declaration that is associated with a value declaration. let _: some P = foo() has no associated value declaration, it's a pattern binding declaration whose pattern does not bind any variables. So there is no value declaration to attach the opaque return type declaration to.

[ashuthe1]

hey i want to work on this issue but i'm a beginner to open source. Could you please guide me through it.

[AnthonyLatsis]

I am removing the good first issue label for now because this

• needs more discussion
• might not be as trivial to implement as originally anticipated
• is low priority