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// RUN: %target-typecheck-verify-swift -enable-objc-interop
// ---------------------------------------------------------------------------
// Mark function's return value as discardable and silence warning
// ---------------------------------------------------------------------------
@discardableResult
func f1() -> [Int] { }
func f2() -> [Int] { }
func f3() { }
func f4<R>(blah: () -> R) -> R { return blah() }
func testGlobalFunctions() -> [Int] {
f1() // okay
f2() // expected-warning {{result of call to 'f2()' is unused}}
_ = f2() // okay
f3() // okay
f4 { 5 } // expected-warning {{result of call to 'f4(blah:)' is unused}}
f4 { } // okay
return f2() // okay
}
attr_discardableResult.f1()
attr_discardableResult.f2() // expected-warning {{result of call to 'f2()' is unused}}
class C1 {
@discardableResult
static func f1Static() -> Int { }
static func f2Static() -> Int { }
@discardableResult
class func f1Class() -> Int { }
class func f2Class() -> Int { }
@discardableResult init() { }
init(foo: Int) { }
@discardableResult
func f1() -> Int { }
func f2() -> Int { }
@discardableResult
func f1Optional() -> Int? { }
func f2Optional() -> Int? { }
@discardableResult
func me() -> Self { return self }
func reallyMe() -> Self { return self }
}
class C2 : C1 {}
func testFunctionsInClass(c1 : C1, c2: C2) {
C1.f1Static() // okay
C1.f2Static() // expected-warning {{result of call to 'f2Static()' is unused}}
_ = C1.f2Static() // okay
C1.f1Class() // okay
C1.f2Class() // expected-warning {{result of call to 'f2Class()' is unused}}
_ = C1.f2Class() // okay
C1() // okay, marked @discardableResult
_ = C1() // okay
C1(foo: 5) // expected-warning {{result of 'C1' initializer is unused}}
_ = C1(foo: 5) // okay
c1.f1() // okay
c1.f2() // expected-warning {{result of call to 'f2()' is unused}}
_ = c1.f2() // okay
c1.f1Optional() // okay
c1.f2Optional() // expected-warning {{result of call to 'f2Optional()' is unused}}
_ = c1.f2Optional() // okay
c1.me() // okay
c2.me() // okay
c1.reallyMe() // expected-warning {{result of call to 'reallyMe()' is unused}}
c2.reallyMe() // expected-warning {{result of call to 'reallyMe()' is unused}}
_ = c1.reallyMe() // okay
_ = c2.reallyMe() // okay
}
struct S1 {
@discardableResult
static func f1Static() -> Int { }
static func f2Static() -> Int { }
@discardableResult init() { }
init(foo: Int) { }
@discardableResult
func f1() -> Int { }
func f2() -> Int { }
@discardableResult
func f1Optional() -> Int? { }
func f2Optional() -> Int? { }
}
func testFunctionsInStruct(s1 : S1) {
S1.f1Static() // okay
S1.f2Static() // expected-warning {{result of call to 'f2Static()' is unused}}
_ = S1.f2Static() // okay
S1() // okay, marked @discardableResult
_ = S1() // okay
S1(foo: 5) // expected-warning {{result of 'S1' initializer is unused}}
_ = S1(foo: 5) // okay
s1.f1() // okay
s1.f2() // expected-warning {{result of call to 'f2()' is unused}}
_ = s1.f2() // okay
s1.f1Optional() // okay
s1.f2Optional() // expected-warning {{result of call to 'f2Optional()' is unused}}
_ = s1.f2Optional() // okay
}
protocol P1 {
@discardableResult
func me() -> Self
func reallyMe() -> Self
}
func testFunctionsInExistential(p1 : P1) {
p1.me() // okay
p1.reallyMe() // expected-warning {{result of call to 'reallyMe()' is unused}}
_ = p1.reallyMe() // okay
}
let x = 4
"Hello \(x+1) world" // expected-warning {{string literal is unused}}
func f(a : () -> Int) {
42 // expected-warning {{integer literal is unused}}
4 + 5 // expected-warning {{result of operator '+' is unused}}
a() // expected-warning {{result of call to function returning 'Int' is unused}}
}
@warn_unused_result func g() -> Int { } // expected-warning {{'warn_unused_result' attribute behavior is now the default}} {{1-21=}}
class X {
@warn_unused_result // expected-warning {{'warn_unused_result' attribute behavior is now the default}} {{3-23=}}
@objc
func h() -> Int { }
}
func testOptionalChaining(c1: C1?, s1: S1?) {
c1?.f1() // okay
c1!.f1() // okay
c1?.f1Optional() // okay
c1!.f1Optional() // okay
c1?.f2() // expected-warning {{result of call to 'f2()' is unused}}
c1!.f2() // expected-warning {{result of call to 'f2()' is unused}}
c1?.f2Optional() // expected-warning {{result of call to 'f2Optional()' is unused}}
c1!.f2Optional() // expected-warning {{result of call to 'f2Optional()' is unused}}
s1?.f1() // okay
s1!.f1() // okay
s1?.f1Optional() // okay
s1!.f1Optional() // okay
s1?.f2() // expected-warning {{result of call to 'f2()' is unused}}
s1!.f2() // expected-warning {{result of call to 'f2()' is unused}}
s1?.f2Optional() // expected-warning {{result of call to 'f2Optional()' is unused}}
s1!.f2Optional() // expected-warning {{result of call to 'f2Optional()' is unused}}
}
// https://github.com/apple/swift/issues/45542
@discardableResult func f_45542(_ closure: @escaping ()->()) -> (()->()) {
closure()
return closure
}
do {
f_45542({}) // okay
}
// https://github.com/apple/swift/issues/50104
class C1_50104 {
@discardableResult required init(input: Int) { }
}
class C2_50104 : C1_50104 {}
do {
C1_50104(input: 10) // okay
C2_50104(input: 10) // okay
}
protocol FooProtocol {}
extension FooProtocol {
@discardableResult
static func returnSomething() -> Bool? {
return true
}
}
class Foo {
var myOptionalFooProtocol: FooProtocol.Type?
func doSomething() {
myOptionalFooProtocol?.returnSomething() // okay
}
}
class Discard {
@discardableResult func bar() -> Int {
return 0
}
func baz() {
self.bar // expected-error {{function is unused}}
bar // expected-error {{function is unused}}
}
}
// https://github.com/apple/swift/issues/54699
struct S_54699 {
@discardableResult
func bar1() -> () -> Void {
return {}
}
@discardableResult
static func bar2() -> () -> Void {
return {}
}
}
do {
S_54699().bar1() // Okay
S_54699.bar2() // Okay
S_54699().bar1 // expected-error {{function is unused}}
S_54699.bar2 // expected-error {{function is unused}}
}
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