[Dependency scanner] Capture Clang context hash and command-line arguments.

Author: DougGregor

include/swift/AST/ModuleDependencies.h

@@ -94,16 +94,26 @@ class ClangModuleDependenciesStorage : public ModuleDependenciesStorageBase {
   /// The module map file used to generate the Clang module.
   const std::string moduleMapFile;
 
+  /// The context hash describing the configuration options for this module.
+  const std::string contextHash;
+
+  /// Partial (Clang) command line that can be used to build this module.
+  const std::vector<std::string> nonPathCommandLine;
+
   /// The file dependencies
   const std::vector<std::string> fileDependencies;
 
   ClangModuleDependenciesStorage(
       const std::string &compiledModulePath,
       const std::string &moduleMapFile,
+      const std::string &contextHash,
+      const std::vector<std::string> &nonPathCommandLine,
       const std::vector<std::string> &fileDependencies
   ) : ModuleDependenciesStorageBase(/*isSwiftModule=*/false,
                                     compiledModulePath),
       moduleMapFile(moduleMapFile),
+      contextHash(contextHash),
+      nonPathCommandLine(nonPathCommandLine),
       fileDependencies(fileDependencies) { }
 
   ModuleDependenciesStorageBase *clone() const override {
@@ -158,11 +168,13 @@ class ModuleDependencies {
   static ModuleDependencies forClangModule(
       const std::string &compiledModulePath,
       const std::string &moduleMapFile,
+      const std::string &contextHash,
+      const std::vector<std::string> &nonPathCommandLine,
       const std::vector<std::string> &fileDependencies) {
     return ModuleDependencies(
-        std::make_unique<ClangModuleDependenciesStorage>(compiledModulePath,
-                                                         moduleMapFile,
-                                                         fileDependencies));
+        std::make_unique<ClangModuleDependenciesStorage>(
+          compiledModulePath, moduleMapFile, contextHash, nonPathCommandLine,
+          fileDependencies));
   }
 
   /// Retrieve the path to the compiled module.

lib/ClangImporter/ClangModuleDependencyScanner.cpp

@@ -209,7 +209,10 @@ static void recordModuleDependencies(
     llvm::StringSet<> alreadyAddedModules;
     auto dependencies = ModuleDependencies::forClangModule(
         clangModuleDep.ImplicitModulePCMPath,
-        clangModuleDep.ClangModuleMapFile, fileDeps);
+        clangModuleDep.ClangModuleMapFile,
+        clangModuleDep.ContextHash,
+        clangModuleDep.NonPathCommandLine,
+        fileDeps);
     for (const auto &moduleName : clangModuleDep.ClangModuleDeps) {
       dependencies.addModuleDependency(moduleName.ModuleName, alreadyAddedModules);
     }

lib/FrontendTool/ScanDependencies.cpp

@@ -301,6 +301,16 @@ static void writeJSON(llvm::raw_ostream &out,
       // Module map file.
       writeJSONSingleField(out, "moduleMapPath",
                            clangDeps->moduleMapFile, 5,
+                           /*trailingComma=*/true);
+
+      // Context hash.
+      writeJSONSingleField(out, "contextHash",
+                           clangDeps->contextHash, 5,
+                           /*trailingComma=*/true);
+
+      // Command line.
+      writeJSONSingleField(out, "commandLine",
+                           clangDeps->nonPathCommandLine, 5,
                            /*trailingComma=*/false);
     }
 

test/ScanDependencies/Inputs/ModuleDependencyGraph.swift

@@ -71,6 +71,13 @@ struct SwiftModuleDetails: Codable {
 struct ClangModuleDetails: Codable {
   /// The path to the module map used to build this module.
   var moduleMapPath: String
+
+  /// The context hash used to discriminate this module file.
+  var contextHash: String
+
+  /// The Clang command line arguments that need to be passed through
+  /// to the -emit-pcm action to build this module.
+  var commandLine: [String] = []
 }
 
 struct ModuleDependencies: Codable {

test/ScanDependencies/module_deps.swift

@@ -74,6 +74,12 @@ import E
 // CHECK: "moduleMapPath"
 // CHECK-SAME: module.modulemap
 
+// CHECK: "contextHash"
+// CHECK-SAME: "{{.*}}"
+
+// CHECK: "commandLine": [
+// CHECK-NEXT: "-remove-preceeding-explicit-module-build-incompatible-options"
+
 /// --------Swift module E
 // CHECK: "swift": "E"
 // CHECK-LABEL: modulePath": "E.swiftmodule"