Revert "[Incremental] Next step towards cross-module incremental dependencies"

Sources/SwiftDriver/IncrementalCompilation/DependencyKey.swift

@@ -24,17 +24,6 @@ import Foundation
   }
 }
 
-/// Since the integration surfaces all externalDependencies to be processed later,
-/// a combination of the dependency and fingerprint are needed.
-public struct FingerprintedExternalDependency: Hashable, Equatable {
-  let externalDependency: ExternalDependency
-  let fingerprint: String?
-  init(_ externalDependency: ExternalDependency, _ fingerprint: String?) {
-    self.externalDependency = externalDependency
-    self.fingerprint = fingerprint
-  }
-  var isIncremental: Bool { fingerprint != nil }
-}
 
 /// A `DependencyKey` carries all of the information necessary to uniquely
 /// identify a dependency node in the graph, and serves as a point of identity
@@ -124,13 +113,6 @@ public struct DependencyKey: Hashable, CustomStringConvertible {
     ///
     /// The `name` of the file is a path to the `swiftdeps` file named in
     /// the output file map for a given Swift file.
-    ///
-    /// If the filename is a swiftmodule, and if it was built by a compilation with
-    /// `-enable-experimental-cross-module-incremental-build`, the swiftmodule file
-    /// contains a special section with swiftdeps information for the module
-    /// in it. In that case the enclosing node should have a fingerprint.
-    ///
-
     case sourceFileProvide(name: String)
     /// A "nominal" type that is used, or defined by this file.
     ///

Sources/SwiftDriver/IncrementalCompilation/IncrementalCompilationState.swift

@@ -442,6 +442,14 @@ extension IncrementalCompilationState {
         reporter: reporter)
 
     let externallyChangedInputs = computeExternallyChangedInputs(
+      forIncrementalExternalDependencies: false,
+      buildTime: outOfDateBuildRecord.buildTime,
+      fileSystem: fileSystem,
+      moduleDependencyGraph: moduleDependencyGraph,
+      reporter: moduleDependencyGraph.reporter)
+
+    let incrementallyExternallyChangedInputs = computeExternallyChangedInputs(
+      forIncrementalExternalDependencies: true,
       buildTime: outOfDateBuildRecord.buildTime,
       fileSystem: fileSystem,
       moduleDependencyGraph: moduleDependencyGraph,
@@ -456,9 +464,9 @@ extension IncrementalCompilationState {
     // Combine to obtain the inputs that definitely must be recompiled.
     let definitelyRequiredInputs =
       Set(changedInputs.map({ $0.filePath }) +
-            externallyChangedInputs +
-            inputsHavingMalformedDependencySources +
-            inputsMissingOutputs)
+            externallyChangedInputs + incrementallyExternallyChangedInputs +
+            inputsHavingMalformedDependencySources
+            + inputsMissingOutputs)
     if let reporter = reporter {
       for scheduledInput in definitelyRequiredInputs.sorted(by: {$0.file.name < $1.file.name}) {
         reporter.report("Queuing (initial):", scheduledInput)
@@ -555,23 +563,26 @@ extension IncrementalCompilationState {
 
   /// Any files dependent on modified files from other modules must be compiled, too.
   private static func computeExternallyChangedInputs(
+    forIncrementalExternalDependencies: Bool,
     buildTime: Date,
     fileSystem: FileSystem,
     moduleDependencyGraph: ModuleDependencyGraph,
     reporter: IncrementalCompilationState.Reporter?
-  ) -> [TypedVirtualPath] {
-    var externalDependencySources = Set<DependencySource>()
-    for extDepAndPrint in moduleDependencyGraph.fingerprintedExternalDependencies {
-      let extDep = extDepAndPrint.externalDependency
+ ) -> [TypedVirtualPath] {
+    var externalDependencySources = Set<ModuleDependencyGraph.DependencySource>()
+    let extDeps = forIncrementalExternalDependencies
+      ? moduleDependencyGraph.incrementalExternalDependencies
+      : moduleDependencyGraph.externalDependencies
+    for extDep in extDeps {
       let extModTime = extDep.file.flatMap {try? fileSystem.getFileInfo($0).modTime}
         ?? Date.distantFuture
       if extModTime >= buildTime {
-        for dependent in moduleDependencyGraph.untracedDependents(of: extDepAndPrint) {
+        for dependent in moduleDependencyGraph.untracedDependents(of: extDep, isIncremental: forIncrementalExternalDependencies) {
           guard let dependencySource = dependent.dependencySource else {
             fatalError("Dependent \(dependent) does not have dependencies file!")
           }
           reporter?.report(
-            "Queuing because of external dependency on newer \(extDep.file?.basename ?? "extDep?")",
+            "Queuing because of \(forIncrementalExternalDependencies ? "incremental " : "")external dependency on newer \(extDep.file?.basename ?? "extDep?")",
             dependencySource.typedFile)
           externalDependencySources.insert(dependencySource)
         }