[SR-2948] Discarding a closure from a @discardableResult function results in a compile error. #45542
Description
| Previous ID | SR-2948 |
| Radar | None |
| Original Reporter | Amnykon (JIRA User) |
| Type | Bug |
| Status | Resolved |
| Resolution | Done |
Additional Detail from JIRA
| Votes | 0 |
| Component/s | Compiler |
| Labels | Bug, StarterBug |
| Assignee | None |
| Priority | Medium |
md5: 021904a7cf17206d058f15ce5ed4b66f
relates to:
- SR-7297 Discarding a function from a discardableResult method causes a compiler error
Issue Description:
A function marked with @discardableResult should not throw an error if it is returning closure is unused.
The current work around is to set _ to the returning closure.
@discardableResult func run (_ closure: @escaping ()->()) -> (()->()) {
closure()
return closure
}
var closure={print(1)}
_ = run(closure)
// Prints 1
_ = run(run(closure))
// Prints 1
// Prints 1
run(closure)
// should Print 1 but errors with:
// discardableResultOfClosure.swift:14:1: error: expression resolves to an unused function
// run(closure)
// ^~~~~~~~~~~~