Warn if a configured rule is not enabled.

Fixes realm#1350

Author: marcelofabri

CHANGELOG.md

@@ -31,7 +31,7 @@
 
 * Make `redundant_objc_attribute` rule autocorrectable.  
   [Daniel Metzing](https://github.com/dirtydanee)
-  
+
 * Add `required_deinit` opt-in rule to ensure that all classes have a deinit
   method. The purpose of this is to make memory leak debugging easier so all
   classes have a place to set a breakpoint to track deallocation.  
@@ -41,7 +41,11 @@
 * `nimble_operator` now warns about `beTrue()` and `beFalse()`.  
   [Igor-Palaguta](https://github.com/Igor-Palaguta)
   [#2613](https://github.com/realm/SwiftLint/issues/2613)
-  
+
+* Warn if a configured rule is not enabled.  
+  [Marcelo Fabri](https://github.com/marcelofabri)
+  [#1350](https://github.com/realm/SwiftLint/issues/1350)
+
 #### Bug Fixes
 
 * Fix `explicit_type_interface` when used in statements.  

Source/SwiftLintFramework/Extensions/Configuration+Parsing.swift

@@ -15,8 +15,8 @@ extension Configuration {
         case analyzerRules = "analyzer_rules"
     }
 
-    private static func validKeys(ruleList: RuleList) -> [String] {
-        return [
+    private static let validGlobalKeys: Set<String> = {
+        return Set([
             Key.cachePath,
             .disabledRules,
             .enabledRules,
@@ -30,7 +30,13 @@ extension Configuration {
             .whitelistRules,
             .indentation,
             .analyzerRules
-        ].map({ $0.rawValue }) + ruleList.allValidIdentifiers()
+        ].map({ $0.rawValue }))
+    }()
+
+    private static func validKeys(ruleList: RuleList) -> Set<String> {
+        var keys = validGlobalKeys
+        keys.formUnion(ruleList.allValidIdentifiers())
+        return keys
     }
 
     private static func getIndentationLogIfInvalid(from dict: [String: Any]) -> IndentationStyle {
@@ -90,7 +96,8 @@ extension Configuration {
                   swiftlintVersion: swiftlintVersion,
                   cachePath: cachePath ?? dict[Key.cachePath.rawValue] as? String,
                   indentation: indentation,
-                  customRulesIdentifiers: customRulesIdentifiers)
+                  customRulesIdentifiers: customRulesIdentifiers,
+                  dict: dict)
     }
 
     private init?(disabledRules: [String],
@@ -107,7 +114,8 @@ extension Configuration {
                   swiftlintVersion: String?,
                   cachePath: String?,
                   indentation: IndentationStyle,
-                  customRulesIdentifiers: [String]) {
+                  customRulesIdentifiers: [String],
+                  dict: [String: Any]) {
         let rulesMode: RulesMode
         if enableAllRules {
             rulesMode = .allEnabled
@@ -123,6 +131,9 @@ extension Configuration {
             rulesMode = .default(disabled: disabledRules, optIn: optInRules + analyzerRules)
         }
 
+        Configuration.validateConfiguredRulesAreEnabled(configurationDictionary: dict, ruleList: ruleList,
+                                                        rulesMode: rulesMode)
+
         self.init(rulesMode: rulesMode,
                   included: included,
                   excluded: excluded,
@@ -178,6 +189,37 @@ extension Configuration {
             queuedPrintError("Configuration contains invalid keys:\n\(invalidKeys)")
         }
     }
+
+    private static func validateConfiguredRulesAreEnabled(configurationDictionary dict: [String: Any],
+                                                          ruleList: RuleList,
+                                                          rulesMode: RulesMode) {
+        for key in dict.keys where !validGlobalKeys.contains(key) {
+            guard let identifier = ruleList.identifier(for: key),
+                let rule = ruleList.list[identifier] else {
+                    continue
+            }
+
+            let message = "Found a configuration for '\(identifier)' rule"
+
+            switch rulesMode {
+            case .allEnabled:
+                return
+            case .whitelisted(let whitelist):
+                if Set(whitelist).isDisjoint(with: rule.description.allIdentifiers) {
+                    queuedPrintError("\(message), but it is not present on " +
+                        "'\(Key.whitelistRules.rawValue)'.")
+                }
+            case let .default(disabled: disabledRules, optIn: optInRules):
+                if rule is OptInRule.Type, Set(optInRules).isDisjoint(with: rule.description.allIdentifiers) {
+                    queuedPrintError("\(message), but it is not enabled on " +
+                        "'\(Key.optInRules.rawValue)'.")
+                } else if Set(disabledRules).isSuperset(of: rule.description.allIdentifiers) {
+                    queuedPrintError("\(message), but it is disabled on " +
+                        "'\(Key.disabledRules.rawValue)'.")
+                }
+            }
+        }
+    }
 }
 
 private func defaultStringArray(_ object: Any?) -> [String] {