Revised for implicit internal: Add redundant internal and fileprivate analysis to go alongside redundant public analysis

.github/workflows/test.yml

@@ -122,6 +122,8 @@ jobs:
       run: ${{ env.swift_build }}
     - name: Scan
       run: ${{ env.periphery_scan }} ${{ matrix.baseline && format('--baseline baselines/{0}', matrix.baseline) || '' }}
+    - name: Clean SwiftPM cache
+      run: rm -rf ~/Library/Caches/org.swift.swiftpm
     - name: Test
       run: ${{ env.swift_test }}
   linux:
@@ -169,5 +171,7 @@ jobs:
       run: ${{ env.swift_build }}
     - name: Scan
       run: ${{ env.periphery_scan }} --baseline baselines/linux.json
+    - name: Clean SwiftPM cache
+      run: rm -rf ~/.cache/org.swift.swiftpm
     - name: Test
       run: ${{ env.swift_test }}

README.md

@@ -28,6 +28,8 @@
     - [Enumerations](#enumerations)
     - [Assign-only Properties](#assign-only-properties)
     - [Redundant Public Accessibility](#redundant-public-accessibility)
+    - [Redundant Internal Accessibility](#redundant-internal-accessibility)
+    - [Redundant Fileprivate Accessibility](#redundant-fileprivate-accessibility)
     - [Unused Imports](#unused-imports)
     - [Objective-C](#objective-c)
     - [Codable](#codable)
@@ -293,6 +295,18 @@ Declarations that are marked `public` yet are not referenced from outside their
 
 This analysis can be disabled with `--disable-redundant-public-analysis`.
 
+### Redundant Internal Accessibility
+
+Declarations that are marked `internal` (or are unmarked, since this is Swift's default access level), yet are not referenced outside the file they're defined in are identified as having redundant internal accessibility. In this scenario, the declaration could be marked `private` or `fileprivate`. Reducing the visibility of declarations — encapsulation — helps with code maintainability and can improve compilation performance.
+
+This analysis can be disabled with `--disable-redundant-internal-analysis`.
+
+### Redundant Fileprivate Accessibility
+
+Declarations that are marked `fileprivate` yet are not accessed from other types within the same file are identified as having redundant fileprivate accessibility. If a `fileprivate` declaration is only used within its own type, it should be marked `private` instead. Reducing the visibility of declarations helps with code maintainability and makes access boundaries clearer.
+
+This analysis can be disabled with `--disable-redundant-fileprivate-analysis`.
+
 ### Unused Imports
 
 Periphery can only detect unused imports of targets it has scanned. It cannot detect unused imports of other targets because the Swift source files are unavailable and uses of `@_exported` cannot be observed. `@_exported` is problematic because it changes the public interface of a target such that the declarations exported by the target are no longer necessarily declared by the imported target. For example, the `Foundation` target exports `Dispatch`, among other targets. If any given source file imports `Foundation` and references `DispatchQueue` but no other declarations from `Foundation`, then the `Foundation` import cannot be removed as it would also make the `DispatchQueue` type unavailable. To avoid false positives, therefore, Periphery only detects unused imports of targets it has scanned.

Sources/BUILD.bazel

@@ -80,7 +80,10 @@ swift_library(
         "SourceGraph/Mutators/ProtocolConformanceReferenceBuilder.swift",
         "SourceGraph/Mutators/ProtocolExtensionReferenceBuilder.swift",
         "SourceGraph/Mutators/PubliclyAccessibleRetainer.swift",
+        "SourceGraph/Mutators/RedundantAccessibilityMarkerShared.swift",
         "SourceGraph/Mutators/RedundantExplicitPublicAccessibilityMarker.swift",
+        "SourceGraph/Mutators/RedundantFilePrivateAccessibilityMarker.swift",
+        "SourceGraph/Mutators/RedundantInternalAccessibilityMarker.swift",
         "SourceGraph/Mutators/RedundantProtocolMarker.swift",
         "SourceGraph/Mutators/ResultBuilderRetainer.swift",
         "SourceGraph/Mutators/StringInterpolationAppendInterpolationRetainer.swift",

Sources/Configuration/Configuration.swift

@@ -80,6 +80,15 @@ public final class Configuration {
     @Setting(key: "disable_redundant_public_analysis", defaultValue: false)
     public var disableRedundantPublicAnalysis: Bool
 
+    @Setting(key: "disable_redundant_internal_analysis", defaultValue: false)
+    public var disableRedundantInternalAnalysis: Bool
+
+    @Setting(key: "disable_redundant_fileprivate_analysis", defaultValue: false)
+    public var disableRedundantFilePrivateAnalysis: Bool
+
+    @Setting(key: "show_nested_redundant_accessibility", defaultValue: false)
+    public var showNestedRedundantAccessibility: Bool
+
     @Setting(key: "disable_unused_import_analysis", defaultValue: false)
     public var disableUnusedImportAnalysis: Bool
 
@@ -224,10 +233,11 @@ public final class Configuration {
 
     // MARK: - Private
 
-    lazy var settings: [any AbstractSetting] = [
+    private lazy var settings: [any AbstractSetting] = [
         $project, $schemes, $excludeTargets, $excludeTests, $indexExclude, $reportExclude, $reportInclude, $outputFormat,
         $retainPublic, $noRetainSPI, $retainFiles, $retainAssignOnlyProperties, $retainAssignOnlyPropertyTypes, $retainObjcAccessible,
         $retainObjcAnnotated, $retainUnusedProtocolFuncParams, $retainSwiftUIPreviews, $disableRedundantPublicAnalysis,
+        $disableRedundantInternalAnalysis, $disableRedundantFilePrivateAnalysis, $showNestedRedundantAccessibility,
         $disableUnusedImportAnalysis, $superfluousIgnoreComments, $retainUnusedImportedModules,
         $externalEncodableProtocols, $externalCodableProtocols, $externalTestCaseClasses, $verbose, $quiet, $color,
         $disableUpdateCheck, $strict, $indexStorePath,
@@ -256,7 +266,7 @@ public final class Configuration {
     }
 }
 
-protocol AbstractSetting {
+private protocol AbstractSetting {
     associatedtype Value
 
     var key: String { get }