Add private_over_fileprivate and strict_fileprivate rules

CHANGELOG.md

@@ -15,6 +15,16 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#1078](https://github.com/realm/SwiftLint/issues/1078)
 
+* Add `private_over_fileprivate` correctable rule to check for top-level usages
+  of  `fileprivate` and recommend `private` instead. This is inline with
+  SE-0169's goal "for `fileprivate` to be used rarely". There is a also a new
+  `strict_fileprivate` opt-in rule that will mark every `fileprivate`
+  as a violation (specially useful with Swift 4).  
+  [Jose Cheyo Jimenez](https://github.com/masters3d)
+  [Marcelo Fabri](https://github.com/marcelofabri)
+  [#1469](https://github.com/realm/SwiftLint/issues/1469)
+  [#1058](https://github.com/realm/SwiftLint/issues/1058)
+
 ##### Bug Fixes
 
 * None.

Rules.md

@@ -59,6 +59,7 @@
 * [Operator Function Whitespace](#operator-function-whitespace)
 * [Overridden methods call super](#overridden-methods-call-super)
 * [Private Outlets](#private-outlets)
+* [Private over fileprivate](#private-over-fileprivate)
 * [Private Unit Test](#private-unit-test)
 * [Prohibited calls to super](#prohibited-calls-to-super)
 * [Protocol Property Accessors Order](#protocol-property-accessors-order)
@@ -71,6 +72,7 @@
 * [Shorthand Operator](#shorthand-operator)
 * [Sorted Imports](#sorted-imports)
 * [Statement Position](#statement-position)
+* [Strict fileprivate](#strict-fileprivate)
 * [Switch Case on Newline](#switch-case-on-newline)
 * [Syntactic Sugar](#syntactic-sugar)
 * [Todo](#todo)
@@ -5875,24 +5877,24 @@ extension String {}
 <summary>Triggering Examples</summary>
 
 ```swift
-private extension String {}
+↓private extension String {}
 ```
 
 ```swift
-public 
+↓public 
  extension String {}
 ```
 
 ```swift
-open extension String {}
+↓open extension String {}
 ```
 
 ```swift
-internal extension String {}
+↓internal extension String {}
 ```
 
 ```swift
-fileprivate extension String {}
+↓fileprivate extension String {}
 ```
 
 </details>
@@ -6852,6 +6854,99 @@ class Foo {
 
 
 
+## Private over fileprivate
+
+Identifier | Enabled by default | Supports autocorrection | Kind 
+--- | --- | --- | ---
+`private_over_fileprivate` | Enabled | Yes | idiomatic
+
+Prefer `private` over `fileprivate` declarations.
+
+### Examples
+
+<details>
+<summary>Non Triggering Examples</summary>
+
+```swift
+extension String {}
+```
+
+```swift
+private extension String {}
+```
+
+```swift
+public 
+ enum MyEnum {}
+```
+
+```swift
+open extension 
+ String {}
+```
+
+```swift
+internal extension String {}
+```
+
+```swift
+extension String {
+fileprivate func Something(){}
+}
+```
+
+```swift
+class MyClass {
+fileprivate let myInt = 4
+}
+```
+
+```swift
+class MyClass {
+fileprivate(set) var myInt = 4
+}
+```
+
+```swift
+struct Outter {
+struct Inter {
+fileprivate struct Inner {}
+}
+}
+```
+
+</details>
+<details>
+<summary>Triggering Examples</summary>
+
+```swift
+↓fileprivate enum MyEnum {}
+```
+
+```swift
+↓fileprivate extension String {}
+```
+
+```swift
+↓fileprivate 
+ extension String {}
+```
+
+```swift
+↓fileprivate extension 
+ String {}
+```
+
+```swift
+↓fileprivate class MyClass {
+fileprivate(set) var myInt = 4
+}
+```
+
+</details>
+
+
+
 ## Private Unit Test
 
 Identifier | Enabled by default | Supports autocorrection | Kind 
@@ -7889,6 +7984,89 @@ catch {
 
 
 
+## Strict fileprivate
+
+Identifier | Enabled by default | Supports autocorrection | Kind 
+--- | --- | --- | ---
+`strict_fileprivate` | Disabled | No | idiomatic
+
+`fileprivate` should be avoided.
+
+### Examples
+
+<details>
+<summary>Non Triggering Examples</summary>
+
+```swift
+extension String {}
+```
+
+```swift
+private extension String {}
+```
+
+```swift
+public 
+ extension String {}
+```
+
+```swift
+open extension 
+ String {}
+```
+
+```swift
+internal extension String {}
+```
+
+</details>
+<details>
+<summary>Triggering Examples</summary>
+
+```swift
+↓fileprivate extension String {}
+```
+
+```swift
+↓fileprivate 
+ extension String {}
+```
+
+```swift
+↓fileprivate extension 
+ String {}
+```
+
+```swift
+extension String {
+↓fileprivate func Something(){}
+}
+```
+
+```swift
+class MyClass {
+↓fileprivate let myInt = 4
+}
+```
+
+```swift
+class MyClass {
+↓fileprivate(set) var myInt = 4
+}
+```
+
+```swift
+struct Outter {
+struct Inter {
+↓fileprivate struct Inner {}
+}
+}
+```
+
+</details>
+
+
+
 ## Switch Case on Newline
 
 Identifier | Enabled by default | Supports autocorrection | Kind 

Source/SwiftLintFramework/Models/MasterRuleList.swift

@@ -67,6 +67,7 @@ public let masterRuleList = RuleList(rules: [
     OperatorUsageWhitespaceRule.self,
     OverriddenSuperCallRule.self,
     PrivateOutletRule.self,
+    PrivateOverFilePrivateRule.self,
     PrivateUnitTestRule.self,
     ProhibitedSuperRule.self,
     ProtocolPropertyAccessorsOrderRule.self,
@@ -79,6 +80,7 @@ public let masterRuleList = RuleList(rules: [
     ShorthandOperatorRule.self,
     SortedImportsRule.self,
     StatementPositionRule.self,
+    StrictFilePrivateRule.self,
     SwitchCaseOnNewlineRule.self,
     SyntacticSugarRule.self,
     TodoRule.self,

Source/SwiftLintFramework/Rules/IdentifierNameRule.swift

@@ -116,7 +116,7 @@ public struct IdentifierNameRule: ASTRule, ConfigurationProviderRule {
     }
 }
 
-fileprivate extension String {
+private extension String {
     var isViolatingCase: Bool {
         let secondIndex = characters.index(after: startIndex)
         let firstCharacter = substring(to: secondIndex)

Source/SwiftLintFramework/Rules/NoExtensionAccessModifier.swift → Source/SwiftLintFramework/Rules/NoExtensionAccessModifierRule.swift

@@ -24,11 +24,11 @@ public struct NoExtensionAccessModifierRule: ASTRule, OptInRule, ConfigurationPr
             "\n\n extension String {}"
             ],
         triggeringExamples: [
-            "private extension String {}",
-            "public \n extension String {}",
-            "open extension String {}",
-            "internal extension String {}",
-            "fileprivate extension String {}"
+            "↓private extension String {}",
+            "↓public \n extension String {}",
+            "↓open extension String {}",
+            "↓internal extension String {}",
+            "↓fileprivate extension String {}"
         ]
     )
 
@@ -47,7 +47,7 @@ public struct NoExtensionAccessModifierRule: ASTRule, OptInRule, ConfigurationPr
         return [
             StyleViolation(ruleDescription: type(of: self).description,
                            severity: configuration.severity,
-                           location: Location(file: file, byteOffset: offset))
+                           location: Location(file: file, byteOffset: aclToken.offset))
         ]
     }
 }