Add Swift compilation flags to enable Clang's validate-per-build-session module behavior

Sources/SwiftDriver/Driver/Driver.swift

@@ -626,6 +626,7 @@ public struct Driver {
                                workingDirectory: workingDirectory,
                                diagnosticEngine: diagnosticEngine)
     Self.validateEmitDependencyGraphArgs(&parsedOptions, diagnosticEngine: diagnosticEngine)
+    Self.validateValidateClangModulesOnceOptions(&parsedOptions, diagnosticEngine: diagnosticEngine)
     Self.validateParseableOutputArgs(&parsedOptions, diagnosticEngine: diagnosticEngine)
     Self.validateCompilationConditionArgs(&parsedOptions, diagnosticEngine: diagnosticEngine)
     Self.validateFrameworkSearchPathArgs(&parsedOptions, diagnosticEngine: diagnosticEngine)
@@ -2701,6 +2702,17 @@ extension Driver {
     }
   }
 
+  static func validateValidateClangModulesOnceOptions(_ parsedOptions: inout ParsedOptions,
+                                                      diagnosticEngine: DiagnosticsEngine) {
+    // '-validate-clang-modules-once' requires '-clang-build-session-file'
+    if parsedOptions.hasArgument(.validateClangModulesOnce) &&
+        !parsedOptions.hasArgument(.clangBuildSessionFile) {
+      diagnosticEngine.emit(.error(Error.optionRequiresAnother(Option.validateClangModulesOnce.spelling,
+                                                               Option.clangBuildSessionFile.spelling)),
+                            location: nil)
+    }
+  }
+
   static func validateEmitDependencyGraphArgs(_ parsedOptions: inout ParsedOptions,
                                               diagnosticEngine: DiagnosticsEngine) {
     // '-print-explicit-dependency-graph' requires '-explicit-module-build'

Sources/SwiftDriver/Jobs/FrontendJobHelpers.swift

@@ -263,6 +263,14 @@ extension Driver {
       commandLine.appendFlag(ver)
     }
 
+    // Pass down -validate-clang-modules-once if we are working with a compiler that
+    // supports it.
+    if isFrontendArgSupported(.validateClangModulesOnce),
+       isFrontendArgSupported(.clangBuildSessionFile) {
+      try commandLine.appendLast(.validateClangModulesOnce, from: &parsedOptions)
+      try commandLine.appendLast(.clangBuildSessionFile, from: &parsedOptions)
+    }
+
     if let workingDirectory = workingDirectory {
       // Add -Xcc -working-directory before any other -Xcc options to ensure it is
       // overridden by an explicit -Xcc -working-directory, although having a

Sources/SwiftOptions/Options.swift

@@ -52,6 +52,7 @@ extension Option {
   public static let candidateModuleFile: Option = Option("-candidate-module-file", .separate, attributes: [.helpHidden, .frontend, .noDriver], metaVar: "<path>", helpText: "Specify Swift module may be ready to use for an interface")
   public static let checkApiAvailabilityOnly: Option = Option("-check-api-availability-only", .flag, attributes: [.helpHidden, .frontend, .noInteractive], helpText: "Only check the availability of the APIs, ignore function bodies")
   public static let checkOnoneCompleteness: Option = Option("-check-onone-completeness", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Print errors if the compile OnoneSupport module is missing symbols")
+  public static let clangBuildSessionFile: Option = Option("-clang-build-session-file", .separate, attributes: [.frontend, .argumentIsPath], helpText: "Use the last modification time of <file> as the underlying Clang build session timestamp")
   public static let clangHeaderExposeDecls: Option = Option("-clang-header-expose-decls=", .joined, attributes: [.helpHidden, .frontend, .noDriver], metaVar: "all-public|has-expose-attr", helpText: "Which declarations should be exposed in the generated clang header.")
   public static let clangTarget: Option = Option("-clang-target", .separate, attributes: [.frontend], helpText: "Separately set the target we should use for internal Clang instance")
   public static let codeCompleteCallPatternHeuristics: Option = Option("-code-complete-call-pattern-heuristics", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Use heuristics to guess whether we want call pattern completions")
@@ -128,6 +129,7 @@ extension Option {
   public static let disableClangimporterSourceImport: Option = Option("-disable-clangimporter-source-import", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Disable ClangImporter and forward all requests straight the DWARF importer.")
   public static let disableCrossModuleOptimization: Option = Option("-disable-cmo", .flag, attributes: [.helpHidden, .frontend], helpText: "Disable cross-module optimization")
   public static let disableCollocateMetadataFunctions: Option = Option("-disable-collocate-metadata-functions", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Disable collocate metadata functions")
+  public static let disableColocateTypeDescriptors: Option = Option("-disable-colocate-type-descriptors", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Disable colocate type descriptors")
   public static let disableConcreteTypeMetadataMangledNameAccessors: Option = Option("-disable-concrete-type-metadata-mangled-name-accessors", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Disable concrete type metadata access by mangled name")
   public static let disableConformanceAvailabilityErrors: Option = Option("-disable-conformance-availability-errors", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Diagnose conformance availability violations as warnings")
   public static let disableConstraintSolverPerformanceHacks: Option = Option("-disable-constraint-solver-performance-hacks", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Disable all the hacks in the constraint solver")
@@ -321,6 +323,7 @@ extension Option {
   public static let enableBridgingPch: Option = Option("-enable-bridging-pch", .flag, attributes: [.helpHidden], helpText: "Enable automatic generation of bridging PCH files")
   public static let enableBuiltinModule: Option = Option("-enable-builtin-module", .flag, attributes: [.frontend, .moduleInterface], helpText: "Enables the explicit import of the Builtin module")
   public static let enableCollocateMetadataFunctions: Option = Option("-enable-collocate-metadata-functions", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Enable collocate metadata functions")
+  public static let enableColocateTypeDescriptors: Option = Option("-enable-colocate-type-descriptors", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Enable colocate type descriptors")
   public static let enableConformanceAvailabilityErrors: Option = Option("-enable-conformance-availability-errors", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Diagnose conformance availability violations as errors")
   public static let copyPropagationStateEQ: Option = Option("-enable-copy-propagation=", .joined, attributes: [.frontend, .noDriver], metaVar: "true|requested-passes-only|false", helpText: "Whether to enable copy propagation")
   public static let enableCopyPropagation: Option = Option("-enable-copy-propagation", .flag, attributes: [.frontend, .noDriver], helpText: "Run SIL copy propagation with lexical lifetimes to shorten object lifetimes while preserving variable lifetimes.")
@@ -714,6 +717,7 @@ extension Option {
   public static let useStaticResourceDir: Option = Option("-use-static-resource-dir", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Use resources in the static resource directory")
   public static let useTabs: Option = Option("-use-tabs", .flag, attributes: [.noInteractive, .noBatch, .indent], helpText: "Use tabs for indentation.", group: .codeFormatting)
   public static let userModuleVersion: Option = Option("-user-module-version", .separate, attributes: [.frontend], metaVar: "<vers>", helpText: "Module version specified from Swift module authors")
+  public static let validateClangModulesOnce: Option = Option("-validate-clang-modules-once", .flag, attributes: [.frontend], helpText: "Don't verify input files for Clang modules if the module has been successfully validated or loaded during this build session")
   public static let validateTbdAgainstIrEQ: Option = Option("-validate-tbd-against-ir=", .joined, attributes: [.helpHidden, .frontend, .noDriver], metaVar: "<level>", helpText: "Compare the symbols in the IR against the TBD file that would be generated.")
   public static let valueRecursionThreshold: Option = Option("-value-recursion-threshold", .separate, attributes: [.helpHidden, .frontend, .doesNotAffectIncrementalBuild], helpText: "Set the maximum depth for direct recursion in value types")
   public static let verifyAdditionalFile: Option = Option("-verify-additional-file", .separate, attributes: [.frontend, .noDriver], helpText: "Verify diagnostics in this file in addition to source files")
@@ -801,6 +805,7 @@ extension Option {
       Option.candidateModuleFile,
       Option.checkApiAvailabilityOnly,
       Option.checkOnoneCompleteness,
+      Option.clangBuildSessionFile,
       Option.clangHeaderExposeDecls,
       Option.clangTarget,
       Option.codeCompleteCallPatternHeuristics,
@@ -877,6 +882,7 @@ extension Option {
       Option.disableClangimporterSourceImport,
       Option.disableCrossModuleOptimization,
       Option.disableCollocateMetadataFunctions,
+      Option.disableColocateTypeDescriptors,
       Option.disableConcreteTypeMetadataMangledNameAccessors,
       Option.disableConformanceAvailabilityErrors,
       Option.disableConstraintSolverPerformanceHacks,
@@ -1070,6 +1076,7 @@ extension Option {
       Option.enableBridgingPch,
       Option.enableBuiltinModule,
       Option.enableCollocateMetadataFunctions,
+      Option.enableColocateTypeDescriptors,
       Option.enableConformanceAvailabilityErrors,
       Option.copyPropagationStateEQ,
       Option.enableCopyPropagation,
@@ -1463,6 +1470,7 @@ extension Option {
       Option.useStaticResourceDir,
       Option.useTabs,
       Option.userModuleVersion,
+      Option.validateClangModulesOnce,
       Option.validateTbdAgainstIrEQ,
       Option.valueRecursionThreshold,
       Option.verifyAdditionalFile,

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -6663,6 +6663,39 @@ final class SwiftDriverTests: XCTestCase {
     XCTAssertTrue(job.commandLine.contains(.path(.absolute(try driver.toolchain.executableDir.parentDirectory.appending(components: "lib", "swift", "host", "plugins")))))
   }
 
+  func testClangModuleValidateOnce() throws {
+    let flagTest = try Driver(args: ["swiftc", "-typecheck", "foo.swift"])
+    guard flagTest.isFrontendArgSupported(.clangBuildSessionFile),
+          flagTest.isFrontendArgSupported(.validateClangModulesOnce) else {
+      return
+    }
+
+    do {
+      var driver = try Driver(args: ["swiftc", "-typecheck", "foo.swift"])
+      let jobs = try driver.planBuild().removingAutolinkExtractJobs()
+      let job = jobs.first!
+      XCTAssertFalse(job.commandLine.contains(.flag("-validate-clang-modules-once")))
+      XCTAssertFalse(job.commandLine.contains(.flag("-clang-build-session-file")))
+    }
+
+    do {
+      try assertDriverDiagnostics(args: ["swiftc", "-validate-clang-modules-once",
+                                         "foo.swift"]) {
+        $1.expect(.error("'-validate-clang-modules-once' cannot be specified if '-clang-build-session-file' is not present"))
+      }
+    }
+
+    do {
+      var driver = try Driver(args: ["swiftc", "-validate-clang-modules-once",
+                                     "-clang-build-session-file", "testClangModuleValidateOnce.session",
+                                     "foo.swift"])
+      let jobs = try driver.planBuild().removingAutolinkExtractJobs()
+      let job = jobs.first!
+      XCTAssertTrue(job.commandLine.contains(.flag("-validate-clang-modules-once")))
+      XCTAssertTrue(job.commandLine.contains(.flag("-clang-build-session-file")))
+    }
+  }
+
   func testRegistrarLookup() throws {
 #if os(Windows)
     let SDKROOT: AbsolutePath = localFileSystem.currentWorkingDirectory!.appending(components: "SDKROOT")