Fix false positive on `private_subject` (#4646)

Fixes #4643

CHANGELOG.md

@@ -14,7 +14,10 @@
 
 #### Bug Fixes
 
-* None.
+* Fix false positives on `private_subject` rule when using
+  subjects inside functions.  
+  [Marcelo Fabri](https://github.com/marcelofabri)
+  [#4643](https://github.com/realm/SwiftLint/issues/4643)
 
 ## 0.50.3: Bundle of Towels
 

Source/SwiftLintFramework/Protocols/SwiftSyntaxRule.swift

@@ -154,6 +154,10 @@ open class ViolationsSyntaxVisitor: SyntaxVisitor {
         skippableDeclarations.contains { $0 == FunctionDeclSyntax.self } ? .skipChildren : .visitChildren
     }
 
+    override open func visit(_ node: SubscriptDeclSyntax) -> SyntaxVisitorContinueKind {
+        skippableDeclarations.contains { $0 == FunctionDeclSyntax.self } ? .skipChildren : .visitChildren
+    }
+
     override open func visit(_ node: VariableDeclSyntax) -> SyntaxVisitorContinueKind {
         skippableDeclarations.contains { $0 == VariableDeclSyntax.self } ? .skipChildren : .visitChildren
     }

Source/SwiftLintFramework/Rules/Lint/PrivateSubjectRule.swift

@@ -29,6 +29,10 @@ private extension PrivateSubjectRule {
     final class Visitor: ViolationsSyntaxVisitor {
         private let subjectTypes: Set<String> = ["PassthroughSubject", "CurrentValueSubject"]
 
+        override var skippableDeclarations: [DeclSyntaxProtocol.Type] {
+            [FunctionDeclSyntax.self, VariableDeclSyntax.self, SubscriptDeclSyntax.self]
+        }
+
         override func visitPost(_ node: VariableDeclSyntax) {
             guard !node.modifiers.isPrivateOrFileprivate,
                   !node.modifiers.containsStaticOrClass else {

Source/SwiftLintFramework/Rules/Lint/PrivateSubjectRuleExamples.swift

@@ -24,7 +24,7 @@ internal struct PrivateSubjectRuleExamples {
         Example(
             #"""
             final class Foobar {
-                private let goodSubject: PassthroughSubject<Bool, Never> = .ini()
+                private let goodSubject: PassthroughSubject<Bool, Never> = .init()
             }
             """#
         ),
@@ -52,7 +52,7 @@ internal struct PrivateSubjectRuleExamples {
         Example(
             #"""
             final class Foobar {
-                private let goodSubject: CurrentValueSubject<String, Never> = .ini("toto")
+                private let goodSubject: CurrentValueSubject<String, Never> = .init("toto")
             }
             """#
         ),
@@ -89,7 +89,7 @@ internal struct PrivateSubjectRuleExamples {
             #"""
             final class Foobar {
                 private let goodSubject:
-                    PassthroughSubject<Bool, Never> = .ini()
+                    PassthroughSubject<Bool, Never> = .init()
             }
             """#
         ),
@@ -100,6 +100,13 @@ internal struct PrivateSubjectRuleExamples {
                     CurrentValueSubject<Bool, Never>(true)
             }
             """#
+        ),
+        Example(
+            """
+            func foo() {
+                let goodSubject = PassthroughSubject<Bool, Never>(true)
+            }
+            """
         )
     ]
 
@@ -135,7 +142,7 @@ internal struct PrivateSubjectRuleExamples {
         Example(
             #"""
             final class Foobar {
-                let goodSubject: PassthroughSubject<Bool, Never> = .ini()
+                let goodSubject: PassthroughSubject<Bool, Never> = .init()
             }
             """#
         ),
@@ -243,7 +250,7 @@ internal struct PrivateSubjectRuleExamples {
             #"""
             final class Foobar {
                 let ↓badSubject:
-                    PassthroughSubject<Bool, Never> = .ini()
+                    PassthroughSubject<Bool, Never> = .init()
             }
             """#
         ),