Dependencies: support optional module dependencies

Author: mirza-garibovic

Sources/SWBCore/Dependencies.swift

@@ -16,6 +16,7 @@ import SWBMacro
 public struct ModuleDependency: Hashable, Sendable, SerializableCodable {
     public let name: String
     public let accessLevel: AccessLevel
+    public let optional: Bool
 
     public enum AccessLevel: String, Hashable, Sendable, CaseIterable, Codable, Serializable, Comparable {
         case Private = "private"
@@ -43,29 +44,25 @@ public struct ModuleDependency: Hashable, Sendable, SerializableCodable {
         }
     }
 
-    public init(name: String, accessLevel: AccessLevel) {
+    public init(name: String, accessLevel: AccessLevel, optional: Bool) {
         self.name = name
         self.accessLevel = accessLevel
+        self.optional = optional
     }
 
     public init(entry: String) throws {
-        var it = entry.split(separator: " ").makeIterator()
-        switch (it.next(), it.next(), it.next()) {
-        case (let .some(name), nil, nil):
-            self.name = String(name)
-            self.accessLevel = .Private
-
-        case (let .some(accessLevel), let .some(name), nil):
-            self.name = String(name)
-            self.accessLevel = try AccessLevel(String(accessLevel))
-
-        default:
-            throw StubError.error("expected 1 or 2 space-separated components in: \(entry)")
+        let re = #/((?<accessLevel>private|package|public)\s+)?(?<name>\w+)(?<optional>\?)?/#
+        guard let match = entry.wholeMatch(of: re) else {
+            throw StubError.error("Invalid module dependency format: \(entry), expected [private|package|public] <name>[?]")
         }
+
+        self.name = String(match.output.name)
+        self.accessLevel = try match.output.accessLevel.map { try AccessLevel(String($0)) } ?? .Private
+        self.optional = match.output.optional != nil
     }
 
     public var asBuildSettingEntry: String {
-        "\(accessLevel == .Private ? "" : "\(accessLevel.rawValue) ")\(name)"
+        "\(accessLevel == .Private ? "" : "\(accessLevel.rawValue) ")\(name)\(optional ? "?" : "")"
     }
 
     public var asBuildSettingEntryQuotedIfNeeded: String {
@@ -121,7 +118,7 @@ public struct ModuleDependenciesContext: Sendable, SerializableCodable {
 
     public func computeUnusedDependencies(usedModuleNames: Set<String>) -> [ModuleDependency] {
         guard validateUnused != .no else { return [] }
-        return moduleDependencies.filter { !usedModuleNames.contains($0.name) }
+        return moduleDependencies.filter { !$0.optional && !usedModuleNames.contains($0.name) }
     }
 
     /// Make diagnostics for missing module dependencies.

Sources/SWBCore/LibSwiftDriver/LibSwiftDriver.swift

@@ -891,5 +891,6 @@ extension ModuleDependency {
     init(_ importInfo: ImportInfo) {
         self.name = importInfo.importIdentifier
         self.accessLevel = .init(importInfo.accessLevel)
+        self.optional = false
     }
 }

Sources/SWBTaskExecution/TaskActions/ClangCompileTaskAction.swift

@@ -388,7 +388,7 @@ public final class ClangCompileTaskAction: TaskAction, BuildValueValidatingTaskA
                 includeFiles.append(file)
             }
         }
-        let moduleDependencies = moduleNames.map { ModuleDependency(name: $0, accessLevel: .Private) }
+        let moduleDependencies = moduleNames.map { ModuleDependency(name: $0, accessLevel: .Private, optional: false) }
         let moduleImports = moduleDependencies.map { DependencyValidationInfo.Import(dependency: $0, importLocations: []) }
         return (moduleImports, includeFiles)
     }

Sources/SWBTaskExecution/TaskActions/ValidateDependenciesTaskAction.swift

@@ -79,7 +79,7 @@ public final class ValidateDependenciesTaskAction: TaskAction {
                     let updatedSwiftMissingDeps: [(ModuleDependency, importLocations: [Diagnostic.Location])] = swiftMissingDeps.map {
                         if let clangMissingDep = clangMissingDepsByName[$0.0.name] {
                             return (
-                                ModuleDependency(name: $0.0.name, accessLevel: max($0.0.accessLevel, clangMissingDep.0.accessLevel)),
+                                ModuleDependency(name: $0.0.name, accessLevel: max($0.0.accessLevel, clangMissingDep.0.accessLevel), optional: $0.0.optional),
                                 $0.importLocations + clangMissingDep.importLocations
                             )
                         } else {

Tests/SWBBuildSystemTests/DependencyValidationTests.swift

@@ -763,7 +763,7 @@ fileprivate struct DependencyValidationTests: CoreBasedTests {
             try await tester.fs.writeFileContents(projectXCConfigPath) { stream in
                 stream <<<
             """
-            MODULE_DEPENDENCIES[target=TargetA] = CoreFoundation Foundation AppKit
+            MODULE_DEPENDENCIES[target=TargetA] = CoreFoundation Foundation AppKit UIKit?
             """
             }
 
@@ -774,7 +774,8 @@ fileprivate struct DependencyValidationTests: CoreBasedTests {
             try await tester.checkBuild(runDestination: .host, buildRequest: buildRequest, persistent: true) { results in
                 guard !results.checkWarning(.prefix("The current toolchain does not support VALIDATE_MODULE_DEPENDENCIES"), failIfNotFound: false) else { return }
 
-                results.checkWarning(.contains("Unused entries in MODULE_DEPENDENCIES: AppKit"))
+                // This diagnostic should only report AppKit because UIKit is marked optional.
+                results.checkWarning(.equal("Unused entries in MODULE_DEPENDENCIES: AppKit (for task: [\"ValidateDependencies\"])"))
             }
         }
     }