Go: Type assertions - is there a bug in the specification?

Question content

go Are there errors in canonical type assertions?

A type assertion used in an assignment statement or initialization of the special form
v, ok = x.(T)
v, ok := x.(T)
var v, ok = x.(T)
var v, ok interface{} = x.(T) // dynamic types of v and ok are T and bool

yields an additional untyped boolean value.

What is the meaning of the last example? var v, good interface {} = x.(t)?

I'm getting an error in go 1.19 syntax Error: Unexpected interface, expecting := or = or comma

Correct Answer

All these lines are trying the same thing: Type assertion for x to type T. The value ok determines whether the assertion was successful. In the last example you provided, the only difference is that instead of determining the types for v and ok, you provided interface{}## for both # type. Declaring v and ok as interface{} does not change the values ​​they contain. It allows you to send them to a function or add them to a collection that requires an interface{} type, at which point they must be asserted again.

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