Remove deprecated inert_defer rule entirely (#5894)

Source/SwiftLintBuiltInRules/Models/BuiltInRules.swift

@@ -92,7 +92,6 @@ public let builtInRules: [any Rule.Type] = [
     ImplicitlyUnwrappedOptionalRule.self,
     InclusiveLanguageRule.self,
     IndentationWidthRule.self,
-    InertDeferRule.self,
     InvalidSwiftLintCommandRule.self,
     IsDisjointRule.self,
     JoinedDefaultParameterRule.self,

Source/SwiftLintBuiltInRules/Rules/Lint/InertDeferRule.swift

@@ -1,116 +0,0 @@
-import SwiftSyntax
-
-// TODO: [12/23/2024] Remove deprecation warning after ~2 years.
-private let warnDeprecatedOnceImpl: Void = {
-    Issue.ruleDeprecated(ruleID: InertDeferRule.identifier).print()
-}()
-
-private func warnDeprecatedOnce() {
-    _ = warnDeprecatedOnceImpl
-}
-
-struct InertDeferRule: SwiftSyntaxRule, OptInRule {
-    var configuration = SeverityConfiguration<Self>(.warning)
-
-    static let description = RuleDescription(
-        identifier: "inert_defer",
-        name: "Inert Defer",
-        description: "If defer is at the end of its parent scope, it will be executed right where it is anyway",
-        kind: .lint,
-        nonTriggeringExamples: [
-            Example("""
-            func example3() {
-                defer { /* deferred code */ }
-
-                print("other code")
-            }
-            """),
-            Example("""
-            func example4() {
-                if condition {
-                    defer { /* deferred code */ }
-                    print("other code")
-                }
-            }
-            """),
-            Example("""
-            func f() {
-                #if os(macOS)
-                defer { print(2) }
-                #else
-                defer { print(3) }
-                #endif
-                print(1)
-            }
-            """, excludeFromDocumentation: true),
-        ],
-        triggeringExamples: [
-            Example("""
-            func example0() {
-                ↓defer { /* deferred code */ }
-            }
-            """),
-            Example("""
-            func example1() {
-                ↓defer { /* deferred code */ }
-                // comment
-            }
-            """),
-            Example("""
-            func example2() {
-                if condition {
-                    ↓defer { /* deferred code */ }
-                    // comment
-                }
-            }
-            """),
-            Example("""
-            func f(arg: Int) {
-                if arg == 1 {
-                    ↓defer { print(2) }
-                    // a comment
-                } else {
-                    ↓defer { print(3) }
-                }
-                print(1)
-                #if os(macOS)
-                ↓defer { print(4) }
-                #else
-                ↓defer { print(5) }
-                #endif
-            }
-            """, excludeFromDocumentation: true),
-        ]
-    )
-
-    func makeVisitor(file: SwiftLintFile) -> ViolationsSyntaxVisitor<ConfigurationType> {
-        warnDeprecatedOnce()
-        return Visitor(configuration: configuration, file: file)
-    }
-}
-
-private extension InertDeferRule {
-    final class Visitor: ViolationsSyntaxVisitor<ConfigurationType> {
-        override func visitPost(_ node: DeferStmtSyntax) {
-            guard node.isLastStatement else {
-                return
-            }
-            if let ifConfigClause = node.parent?.parent?.parent?.as(IfConfigClauseSyntax.self),
-               ifConfigClause.parent?.parent?.isLastStatement == false {
-                return
-            }
-
-            violations.append(node.deferKeyword.positionAfterSkippingLeadingTrivia)
-        }
-    }
-}
-
-private extension SyntaxProtocol {
-    var isLastStatement: Bool {
-        if let codeBlockItem = parent?.as(CodeBlockItemSyntax.self),
-           let codeBlockList = codeBlockItem.parent?.as(CodeBlockItemListSyntax.self) {
-            return codeBlockList.last == codeBlockItem
-        }
-        return false
-    }
-}