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swift-mirror/test/decl/var/usage.swift

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// RUN: %target-typecheck-verify-swift
// <rdar://problem/20872721> QoI: warn about unused variables
// <rdar://problem/15975935> warning that you can use 'let' not 'var'
// <rdar://problem/18876585> Compiler should warn me if I set a parameter as 'var' but never modify it
func basicTests() -> Int {
let x = 42 // expected-warning {{immutable value 'x' was never used; consider replacing with assignment to '_' or removing it}} {{3-8=_}}
var y = 12 // expected-warning {{variable 'y' was never mutated; consider changing to 'let' constant}} {{3-6=let}}
_ = 42 // ok
_ = 42 // ok
return y
}
func mutableParameter(_ a : Int, h : Int, var i : Int, j: Int, g: Int) -> Int { // expected-warning {{'var' in this position is interpreted as an argument label}} {{43-46=`var`}}
i += 1 // expected-error {{left side of mutating operator isn't mutable: 'i' is a 'let' constant}}
var j = j
swap(&i, &j) // expected-error {{cannot pass immutable value as inout argument: 'i' is a 'let' constant}}
return i+g
}
struct X {
func f() {}
mutating func g() {}
}
func testStruct() {
let a = X()
a.f()
var b = X()
b.g()
var c = X() // expected-warning {{variable 'c' was never mutated; consider changing to 'let' constant}} {{3-6=let}}
c.f()
}
func takeClosure(_ fn : () -> ()) {}
class TestClass {
func f() {
takeClosure { [weak self] in // self is mutable but never mutated. Ok because it is weak
self?.f()
}
}
}
enum TestEnum {
case Test(Int, Int, Int)
}
func testEnum() -> Int {
let ev = TestEnum.Test(5, 6, 7)
switch ev {
case .Test(var i, var j, var k): // expected-warning {{variable 'i' was never mutated; consider changing to 'let' constant}} {{14-17=let}}
// expected-warning@-1 {{variable 'j' was never mutated; consider changing to 'let' constant}} {{21-24=let}}
// expected-warning@-2 {{variable 'k' was never mutated; consider changing to 'let' constant}} {{28-31=let}}
return i + j + k
default:
return 0
}
}
func nestedFunction() -> Int {
var x = 42 // No warning about being never-set.
func g() {
x = 97
var q = 27 // expected-warning {{variable 'q' was never used}} {{5-10=_}}
}
g()
return x
}
func neverRead() {
var x = 42 // expected-warning {{variable 'x' was written to, but never read}}
x = 97
x = 123
}
func property() -> Int {
var p : Int { // everything ok
return 42
}
return p
}
func testInOut(_ x : inout Int) { // Ok.
}
struct TestStruct {
var property = 42
var mutatingProperty: Int {
mutating get { return 0 }
mutating set {}
}
var nonmutatingProperty: Int {
nonmutating get { return 0 }
nonmutating set {}
}
subscript(mutating index: Int) -> Int {
mutating get { return 0 }
mutating set {}
}
subscript(nonmutating index: Int) -> Int {
nonmutating get { return 0 }
nonmutating set {}
}
}
func testStructMember() -> TestStruct {
var x = TestStruct() // ok
x.property = 17
return x
}
func testMutatingProperty_get() -> TestStruct {
var x = TestStruct() // ok
_ = x.mutatingProperty
return x
}
func testMutatingProperty_set() -> TestStruct {
var x = TestStruct() // ok
x.mutatingProperty = 17
return x
}
func testNonmutatingProperty_get() -> TestStruct {
var x = TestStruct() // expected-warning {{variable 'x' was never mutated; consider changing to 'let' constant}}
_ = x.nonmutatingProperty
return x
}
func testNonmutatingProperty_set() -> TestStruct {
var x = TestStruct() // expected-warning {{variable 'x' was never mutated; consider changing to 'let' constant}}
x.nonmutatingProperty = 17
return x
}
func testMutatingSubscript_get() -> TestStruct {
var x = TestStruct() // ok
_ = x[mutating: 4]
return x
}
func testMutatingSubscript_set() -> TestStruct {
var x = TestStruct() // ok
x[mutating: 4] = 17
return x
}
func testNonmutatingSubscript_get() -> TestStruct {
var x = TestStruct() // expected-warning {{variable 'x' was never mutated; consider changing to 'let' constant}}
_ = x[nonmutating: 4]
return x
}
func testNonmutatingSubscript_set() -> TestStruct {
var x = TestStruct() // expected-warning {{variable 'x' was never mutated; consider changing to 'let' constant}}
x[nonmutating: 4] = 17
return x
}
func testSubscript() -> [Int] {
var x = [1,2,3] // ok
x[1] = 27
return x
}
func testSubscriptNeverMutated() -> [Int] {
var x = [1,2,3] // expected-warning {{variable 'x' was never mutated; consider changing to 'let' constant}}
_ = x[1]
return x
}
func testTuple(_ x : Int) -> Int {
var x = x
var y : Int // Ok, stored by a tuple
(x, y) = (1,2)
_ = x
_ = y
return y
}
struct TestComputedPropertyStruct {
var x : Int {
get {}
nonmutating set {}
}
}
func test() {
let v = TestComputedPropertyStruct()
v.x = 42
var v2 = TestComputedPropertyStruct() // expected-warning {{variable 'v2' was never mutated; consider changing to 'let' constant}} {{3-6=let}}
v2.x = 42
}
func test4() {
// expected-warning @+1 {{variable 'dest' was never mutated; consider changing to 'let' constant}} {{3-6=let}}
var dest = UnsafeMutablePointer<Int>(bitPattern: 0)!
dest[0] = 0
}
func testTuple() {
var tup : (x:Int, y:Int) // expected-warning {{variable 'tup' was written to, but never read}}
tup.x = 1
// <rdar://problem/20927707> QoI: 'variable was never mutated' noisy when only part of a destructured tuple is mutated
var (tupA, tupB) = (1,2) // don't warn about tupB being changeable to a 'let'.
tupA += tupB
}
/// <rdar://problem/20911927> False positive in the "variable was never mutated" warning with IUO
func testForceValueExpr() {
var a: X! = nil // no warning, mutated through the !
a!.g()
}
// <rdar://problem/20894455> "variable was never mutated" diagnostic does not take #if into account
func testBuildConfigs() {
let abc = 42 // no warning.
var mut = 18 // no warning.
let other = 15 // no warning?
var othermut = 15 // no warning
#if false
mut = abc // These uses prevent abc/mut from being unused/unmutated.
#endif
#if compiler(>=10.0)
othermut = other // This use prevents other/othermut from being unused/unmutated
#endif
}
func postfixSuppression() -> Int {
let x = 10 // used to have warning: ... 'x' was never used...
return 5
#if FLAG
.modifier(x)
#endif
}
// same as above, but with a guard statement
func testGuardWithPoundIf(x: Int?) {
guard let x = x else { return }
#if false
_ = x
#endif
}
// <rdar://problem/21091625> Bogus 'never mutated' warning when protocol variable is mutated only by mutating method
protocol Fooable {
mutating func mutFoo()
func immutFoo()
var mutatingProperty: Int { mutating get mutating set }
var nonmutatingProperty: Int { nonmutating get nonmutating set }
}
func testOpenExistential(_ x: Fooable,
y: Fooable) {
var x = x
let y = y
x.mutFoo()
y.immutFoo()
}
func testOpenExistential_mutatingProperty_get(p: Fooable) {
var x = p
_ = x.mutatingProperty
}
func testOpenExistential_mutatingProperty_set(p: Fooable) {
var x = p
x.mutatingProperty = 4
}
func testOpenExistential_nonmutatingProperty_get(p: Fooable) {
var x = p // expected-warning {{variable 'x' was never mutated; consider changing to 'let' constant}}
_ = x.nonmutatingProperty
}
func testOpenExistential_nonmutatingProperty_set(p: Fooable) {
var x = p // expected-warning {{variable 'x' was never mutated; consider changing to 'let' constant}}
x.nonmutatingProperty = 4
}
func couldThrow() throws {}
func testFixitsInStatementsWithPatterns(_ a : Int?) {
if var b = a, // expected-warning {{variable 'b' was never mutated; consider changing to 'let' constant}} {{6-9=let}}
var b2 = a { // expected-warning {{variable 'b2' was never mutated; consider changing to 'let' constant}} {{7-10=let}}
_ = b
_ = b2
}
for var b in [42] { // expected-warning {{variable 'b' was never mutated; consider removing 'var' to make it constant}} {{7-11=}}
_ = b
}
do {
try couldThrow()
} catch var err { // expected-warning {{variable 'err' was never mutated; consider changing to 'let' constant}} {{11-14=let}}
_ = err
}
switch a {
case var b: _ = b // expected-warning {{variable 'b' was never mutated; consider changing to 'let' constant}} {{10-13=let}}
}
}
// <rdar://22774938> QoI: "never used" in an "if let" should rewrite expression to use != nil
func test(_ a : Int?, b : Any) {
if true == true, let x = a { // expected-warning {{immutable value 'x' was never used; consider replacing with '_' or removing it}} {{20-25=_}}
}
if let x = a, let y = a { // expected-warning {{immutable value 'x' was never used; consider replacing with '_' or removing it}} {{6-11=_}}
_ = y
}
// Simple case, insert a comparison with nil.
if let x = a { // expected-warning {{value 'x' was defined but never used; consider replacing with boolean test}} {{6-14=}} {{15-15= != nil}}
}
// General case, need to insert parentheses.
if let x = a ?? a {} // expected-warning {{value 'x' was defined but never used; consider replacing with boolean test}} {{6-14=(}} {{20-20=) != nil}}
// Special case, we can turn this into an 'is' test.
if let x = b as? Int { // expected-warning {{value 'x' was defined but never used; consider replacing with boolean test}} {{6-14=}} {{16-19=is}}
}
// Special case, turn these into an 'is' test with optional value.
// https://github.com/apple/swift/issues/56998
let bb: Any? = 3
if let bbb = bb as? Int {} // expected-warning {{value 'bbb' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{19-22=is}}
if let bbb = (bb) as? Int {} // expected-warning {{value 'bbb' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{21-24=is}}
func aa() -> Any? { return 1 }
if let aaa = aa() as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{21-24=is}}
if let aaa = (aa()) as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{23-26=is}}
func bb() -> Any { return 1 }
if let aaa = aa() as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{21-24=is}}
if let aaa = (aa()) as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{23-26=is}}
func throwingAA() throws -> Any? { return 1 }
do {
if let aaa = try! throwingAA() as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{8-18=}} {{36-39=is}}
if let aaa = (try! throwingAA()) as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{8-18=}} {{38-41=is}}
if let aaa = try throwingAA() as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{8-18=}} {{35-38=is}}
if let aaa = (try throwingAA()) as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{8-18=}} {{37-40=is}}
} catch { }
if let aaa = try? throwingAA() as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{6-16=(}} {{41-41=) != nil}}
if let aaa = (try? throwingAA()) as? Int {} // expected-warning {{value 'aaa' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{36-39=is}}
func throwingBB() throws -> Any { return 1 }
do {
if let bbb = try! throwingBB() as? Int {} // expected-warning {{value 'bbb' was defined but never used; consider replacing with boolean test}} {{8-18=}} {{36-39=is}}
if let bbb = (try! throwingBB()) as? Int {} // expected-warning {{value 'bbb' was defined but never used; consider replacing with boolean test}} {{8-18=}} {{38-41=is}}
if let bbb = try throwingBB() as? Int {} // expected-warning {{value 'bbb' was defined but never used; consider replacing with boolean test}} {{8-18=}} {{35-38=is}}
if let bbb = (try throwingBB()) as? Int {} // expected-warning {{value 'bbb' was defined but never used; consider replacing with boolean test}} {{8-18=}} {{37-40=is}}
} catch { }
if let bbb = try? throwingBB() as? Int {} // expected-warning {{value 'bbb' was defined but never used; consider replacing with boolean test}} {{6-16=(}} {{41-41=) != nil}}
if let bbb = (try? throwingBB()) as? Int {} // expected-warning {{value 'bbb' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{36-39=is}}
let cc: (Any?, Any) = (1, 2)
if let (cc1, cc2) = cc as? (Int, Int) {} // expected-warning {{immutable value 'cc1' was never used; consider replacing with '_' or removing it}} expected-warning {{immutable value 'cc2' was never used; consider replacing with '_' or removing it}}
// https://github.com/apple/swift/issues/43725
let xxx: Int? = 0
if let yyy = xxx { } // expected-warning{{with boolean test}} {{6-16=}} {{19-19= != nil}}
var zzz: Int? = 0
zzz = 1
if let yyy = zzz { } // expected-warning{{with boolean test}} {{6-16=}} {{19-19= != nil}}
if let yyy = zzz ?? xxx { } // expected-warning{{with boolean test}} {{6-16=(}} {{26-26=) != nil}}
}
func test2() {
let a = 4 // expected-warning {{initialization of immutable value 'a' was never used; consider replacing with assignment to '_' or removing it}} {{3-8=_}}
var ( b ) = 6 // expected-warning {{initialization of variable 'b' was never used; consider replacing with assignment to '_' or removing it}} {{3-12=_}}
var c: Int = 4 // expected-warning {{variable 'c' was never used; consider replacing with '_' or removing it}} {{7-8=_}}
let (d): Int = 9 // expected-warning {{immutable value 'd' was never used; consider replacing with '_' or removing it}} {{8-9=_}}
}
let optionalString: String? = "check"
if let string = optionalString {} // expected-warning {{value 'string' was defined but never used; consider replacing with boolean test}} {{4-17=}} {{31-31= != nil}}
let optionalAny: Any? = "check"
if let string = optionalAny as? String {} // expected-warning {{value 'string' was defined but never used; consider replacing with boolean test}} {{4-17=}} {{29-32=is}}
// Due to the complexities of global variable tracing, these will not generate warnings
let unusedVariable = ""
var unNeededVar = false
if unNeededVar {}
guard let foo = optionalAny else {}
for i in 0..<10 { // expected-warning {{immutable value 'i' was never used; consider replacing with '_' or removing it}} {{5-6=_}}
print("")
}
// https://github.com/apple/swift/issues/45026
do {
let x: Int // expected-warning {{immutable value 'x' was never used; consider removing it}}
x = 42
}
// Thttps://github.com/apple/swift/issues/43576
do {
var noOpSetter: String {
get { return "" }
set { } // No warning
}
var suspiciousSetter: String {
get { return "" }
set {
print(suspiciousSetter) // expected-warning {{setter argument 'newValue' was never used, but the property was accessed}} expected-note {{did you mean to use 'newValue' instead of accessing the property's current value?}} {{13-29=newValue}}
}
}
struct MemberGetterStruct {
var suspiciousSetter: String {
get { return "" }
set {
print(suspiciousSetter) // expected-warning {{setter argument 'newValue' was never used, but the property was accessed}} expected-note {{did you mean to use 'newValue' instead of accessing the property's current value?}} {{15-31=newValue}}
}
}
}
class MemberGetterClass {
var suspiciousSetter: String {
get { return "" }
set {
print(suspiciousSetter) // expected-warning {{setter argument 'newValue' was never used, but the property was accessed}} expected-note {{did you mean to use 'newValue' instead of accessing the property's current value?}} {{15-31=newValue}}
}
}
}
var namedSuspiciousSetter: String {
get { return "" }
set(parameter) {
print(namedSuspiciousSetter) // expected-warning {{setter argument 'parameter' was never used, but the property was accessed}} expected-note {{did you mean to use 'parameter' instead of accessing the property's current value?}} {{13-34=parameter}}
}
}
var okSetter: String {
get { return "" }
set { print(newValue) } // No warning
}
var multiTriggerSetter: String {
get { return "" }
set {
print(multiTriggerSetter) // expected-warning {{setter argument 'newValue' was never used, but the property was accessed}} expected-note {{did you mean to use 'newValue' instead of accessing the property's current value?}} {{13-31=newValue}}
print(multiTriggerSetter)
}
}
}
struct MemberGetterExtension {}
extension MemberGetterExtension {
var suspiciousSetter: String {
get { return "" }
set {
print(suspiciousSetter) // expected-warning {{setter argument 'newValue' was never used, but the property was accessed}} expected-note {{did you mean to use 'newValue' instead of accessing the property's current value?}} {{13-29=newValue}}
}
}
}
func testLocalFunc() {
var unusedVar = 0
// expected-warning@-1 {{initialization of variable 'unusedVar' was never used; consider replacing with assignment to '_' or removing it}}
var notMutatedVar = 0
// expected-warning@-1 {{variable 'notMutatedVar' was never mutated; consider changing to 'let' constant}}
var mutatedVar = 0
// expected-warning@-1 {{variable 'mutatedVar' was written to, but never read}}
func localFunc() {
_ = notMutatedVar
mutatedVar = 1
}
}
// False positive "'var' was never mutated" warning - rdar://60563962
func testForwardReferenceCapture() {
func innerFunc() {
x = 10
}
var x: Int = 1
innerFunc()
print(x)
}
// rdar://47240768 Expand the definition of "simple" pattern to variables bound in patterns
func testVariablesBoundInPatterns() {
enum StringB {
case simple(b: Bool)
case tuple(b: (Bool, Bool))
case optional(b: Bool?)
}
// Because Swift enables all kinds of creative binding forms, make sure that
// variable patterns occurring directly under a `let` or `var` have that
// introducer stripped by the fixit. All other cases are currently too
// complicated for the VarDeclUsageChecker.
switch StringB.simple(b: true) {
case .simple(b: let b) where false: // expected-warning {{immutable value 'b' was never used; consider replacing with '_' or removing it}} {{19-24=_}}
break
case .simple(b: var b) where false: // expected-warning {{variable 'b' was never used; consider replacing with '_' or removing it}} {{19-24=_}}
break
case var .simple(b: b): // expected-warning {{variable 'b' was never used; consider replacing with '_' or removing it}} {{23-24=_}}
break
case .tuple(b: let (b1, b2)) where false:
// expected-warning@-1 {{immutable value 'b1' was never used; consider replacing with '_' or removing it}} {{23-25=_}}
// expected-warning@-2 {{immutable value 'b2' was never used; consider replacing with '_' or removing it}} {{27-29=_}}
break
case .tuple(b: (let b1, let b2)) where false:
// expected-warning@-1 {{immutable value 'b1' was never used; consider replacing with '_' or removing it}} {{19-25=_}}
// expected-warning@-2 {{immutable value 'b2' was never used; consider replacing with '_' or removing it}} {{27-33=_}}
break
case .tuple(b: (var b1, var b2)) where false:
// expected-warning@-1 {{variable 'b1' was never used; consider replacing with '_' or removing it}} {{19-25=_}}
// expected-warning@-2 {{variable 'b2' was never used; consider replacing with '_' or removing it}} {{27-33=_}}
break
case var .tuple(b: (b1, b2)) where false:
// expected-warning@-1 {{variable 'b1' was never used; consider replacing with '_' or removing it}} {{23-25=_}}
// expected-warning@-2 {{variable 'b2' was never used; consider replacing with '_' or removing it}} {{27-29=_}}
break
case .tuple(b: let b): // expected-warning {{immutable value 'b' was never used; consider replacing with '_' or removing it}} {{18-23=_}}
break
case .optional(b: let x?) where false: // expected-warning {{immutable value 'x' was never used; consider replacing with '_' or removing it}} {{25-26=_}}
break
case .optional(b: let .some(x)) where false: // expected-warning {{immutable value 'x' was never used; consider replacing with '_' or removing it}} {{31-32=_}}
break
case let .optional(b: x?): // expected-warning {{immutable value 'x' was never used; consider replacing with '_' or removing it}} {{25-26=_}}
break
case let .optional(b: .none): // expected-warning {{'let' pattern has no effect; sub-pattern didn't bind any variables}} {{8-12=}}
break
}
}
// https://github.com/apple/swift/issues/56998
func testUselessCastWithInvalidParam(foo: Any?) -> Int {
class Foo { }
if let bar = foo as? Foo { return 42 } // expected-warning {{value 'bar' was defined but never used; consider replacing with boolean test}} {{6-16=}} {{20-23=is}}
else { return 54 }
}
// https://github.com/swiftlang/swift/issues/72811
func testEnumeratedForLoop(a: [Int]) {
for var (b, c) in a.enumerated() { // expected-warning {{variable 'b' was never mutated; consider changing the pattern to 'case (..., let b, ...)'}}
c = b
let _ = c
}
}
// https://github.com/swiftlang/swift/issues/79555
final class A {
var x: () -> Void {
{ [weak self] in // Used to warn: variable 'self' was written to, but never read
#if NOT_PROCESSED
self?.f()
#endif
}
}
func f() {}
}