(edited)

kateinoigakukun

func foo(block: (Int, Int) -> Int) {} foo { $0 }

Version:

swift-4.1-RELEASE

Output:

Error:

/usercode/main.swift:3:5: error: contextual closure type '(Int, Int) -> Int' expects 2 arguments, but 1 was used in closure body foo { $0 } ^ ,<#arg#>