Revert "[Explicit Module Builds] Re-scan all clang modules against all targets against which they will be built."

Author: artemcm

Sources/SwiftDriver/Driver/Driver.swift

@@ -205,7 +205,7 @@ public struct Driver {
   /// A collection describing external dependencies for the current main module that may be invisible to
   /// the driver itself, but visible to its clients (e.g. build systems like SwiftPM). Along with the external dependencies'
   /// module dependency graphs.
-  @_spi(Testing) public var externalDependencyArtifactMap: ExternalDependencyArtifactMap? = nil
+  internal var externalDependencyArtifactMap: ExternalDependencyArtifactMap? = nil
 
   /// Handler for emitting diagnostics to stderr.
   public static let stderrDiagnosticsHandler: DiagnosticsEngine.DiagnosticsHandler = { diagnostic in
@@ -1005,9 +1005,6 @@ extension Driver {
       case .scanDependencies:
         compilerOutputType = .jsonDependencies
 
-      case .scanClangDependencies:
-        compilerOutputType = .jsonClangDependencies
-
       default:
         fatalError("unhandled output mode option \(outputOption)")
       }

Sources/SwiftDriver/Explicit Module Builds/ClangVersionedDependencyResolution.swift

@@ -34,6 +34,9 @@ public typealias ExternalDependencyArtifactMap =
   /// The toolchain to be used for frontend job generation.
   private let toolchain: Toolchain
 
+  /// A collection of external dependency modules, and their binary module file paths and dependency graph.
+  internal let externalDependencyArtifactMap: ExternalDependencyArtifactMap
+
   /// The file system which we should interact with.
   /// FIXME: Our end goal is to not have any direct filesystem manipulation in here, but  that's dependent on getting the
   /// dependency scanner/dependency job generation  moved into a Job.
@@ -45,11 +48,12 @@ public typealias ExternalDependencyArtifactMap =
   /// dependency scanner/dependency job generation  moved into a Job.
   private let temporaryDirectory: AbsolutePath
 
-  public init(dependencyGraph: InterModuleDependencyGraph,
-              toolchain: Toolchain,
-              fileSystem: FileSystem) throws {
+  public init(dependencyGraph: InterModuleDependencyGraph, toolchain: Toolchain,
+              fileSystem: FileSystem,
+              externalDependencyArtifactMap: ExternalDependencyArtifactMap) throws {
     self.dependencyGraph = dependencyGraph
     self.toolchain = toolchain
+    self.externalDependencyArtifactMap = externalDependencyArtifactMap
     self.fileSystem = fileSystem
     self.temporaryDirectory = try determineTempDirectory()
   }
@@ -115,6 +119,11 @@ public typealias ExternalDependencyArtifactMap =
   /// - Generate Job: S1
   ///
   mutating public func generateExplicitModuleDependenciesBuildJobs() throws -> [Job] {
+    // Resolve placeholder dependencies in the dependency graph, if any.
+    if (!externalDependencyArtifactMap.isEmpty) {
+      try resolvePlaceholderDependencies()
+    }
+
     // Compute jobs for all main module dependencies
     var mainModuleInputs: [TypedVirtualPath] = []
     var mainModuleCommandLine: [Job.ArgTemplate] = []
@@ -435,7 +444,7 @@ extension ExplicitModuleBuildHandler {
 
 /// Encapsulates some of the common queries of the ExplicitModuleBuildeHandler with error-checking
 /// on the dependency graph's structure.
-internal extension InterModuleDependencyGraph {
+private extension InterModuleDependencyGraph {
   func moduleInfo(of moduleId: ModuleDependencyId) throws -> ModuleInfo {
     guard let moduleInfo = modules[moduleId] else {
       throw Driver.Error.missingModuleDependency(moduleId.moduleName)

Sources/SwiftDriver/Explicit Module Builds/ExplicitModuleBuildHandler.swift

@@ -11,11 +11,10 @@
 //===----------------------------------------------------------------------===//
 import Foundation
 import TSCBasic
-import SwiftOptions
 
 extension Driver {
   /// Precompute the dependencies for a given Swift compilation, producing a
-  /// dependency graph including all Swift and C module files and
+  /// complete dependency graph including all Swift and C module files and
   /// source files.
   mutating func dependencyScanningJob() throws -> Job {
     var inputs: [TypedVirtualPath] = []
@@ -74,66 +73,4 @@ extension Driver {
     try fileSystem.writeFileContents(placeholderMapFilePath, bytes: ByteString(contents))
     return placeholderMapFilePath
   }
-
-  /// Compute the dependencies for a given Clang module, by invoking the Clang dependency scanning action
-  /// with the given module's name and a set of arguments (including the target version)
-  mutating func clangDependencyScanningJob(moduleId: ModuleDependencyId,
-                                           pcmArgs: [String]) throws -> Job {
-    var inputs: [TypedVirtualPath] = []
-
-    // Aggregate the fast dependency scanner arguments
-    var commandLine: [Job.ArgTemplate] = swiftCompilerPrefixArgs.map { Job.ArgTemplate.flag($0) }
-    commandLine.appendFlag("-frontend")
-    commandLine.appendFlag("-scan-clang-dependencies")
-
-    try addCommonFrontendOptions(commandLine: &commandLine, inputs: &inputs,
-                                 bridgingHeaderHandling: .precompiled,
-                                 moduleDependencyGraphUse: .dependencyScan)
-
-    // Ensure the `-target` option is inherited from the dependent Swift module's PCM args
-    if let targetOptionIndex = pcmArgs.firstIndex(of: Option.target.spelling) {
-      // PCM args are formulated as Clang command line options specified with:
-      // -Xcc <option> -Xcc <option_value>
-      assert(pcmArgs.count > targetOptionIndex + 1 && pcmArgs[targetOptionIndex + 1] == "-Xcc")
-      let pcmArgTriple = Triple(pcmArgs[targetOptionIndex + 2])
-      // Override the invocation's default target argument by appending the one extracted from
-      // the pcmArgs
-      commandLine.appendFlag(.target)
-      commandLine.appendFlag(pcmArgTriple.triple)
-    }
-
-    // Add the PCM args specific to this scan
-    pcmArgs.forEach { commandLine.appendFlags($0) }
-
-    // This action does not require any input files, but all frontend actions require
-    // at least one input so pick any input of the current compilation.
-    let inputFile = inputFiles.first { $0.type == .swift }
-    commandLine.appendPath(inputFile!.file)
-    inputs.append(inputFile!)
-
-    commandLine.appendFlags("-module-name", moduleId.moduleName)
-    // Construct the scanning job.
-    return Job(moduleName: moduleOutputInfo.name,
-               kind: .scanClangDependencies,
-               tool: VirtualPath.absolute(try toolchain.getToolPath(.swiftCompiler)),
-               commandLine: commandLine,
-               displayInputs: inputs,
-               inputs: inputs,
-               outputs: [TypedVirtualPath(file: .standardOutput, type: .jsonDependencies)],
-               supportsResponseFiles: true)
-  }
-
-  mutating func scanClangModule(moduleId: ModuleDependencyId, pcmArgs: [String])
-  throws -> InterModuleDependencyGraph {
-    let clangDependencyScannerJob = try clangDependencyScanningJob(moduleId: moduleId,
-                                                                   pcmArgs: pcmArgs)
-    let forceResponseFiles = parsedOptions.hasArgument(.driverForceResponseFiles)
-
-    let dependencyGraph =
-      try self.executor.execute(job: clangDependencyScannerJob,
-                                capturingJSONOutputAs: InterModuleDependencyGraph.self,
-                                forceResponseFiles: forceResponseFiles,
-                                recordedInputModificationDates: recordedInputModificationDates)
-    return dependencyGraph
-  }
 }