[Dependency Scanner] Use Clang scanner's module name query API instead of creating a dummy file

Author: artemcm

lib/ClangImporter/ClangModuleDependencyScanner.cpp

@@ -29,12 +29,6 @@ using namespace clang::tooling;
 using namespace clang::tooling::dependencies;
 
 class swift::ClangModuleDependenciesCacheImpl {
-  /// Cache the names of the files used for the "import hack" to compute module
-  /// dependencies.
-  /// FIXME: This should go away once Clang's dependency scanning library
-  /// can scan by module name.
-  llvm::StringMap<std::string> importHackFileCache;
-
 public:
   /// Set containing all of the Clang modules that have already been seen.
   llvm::StringSet<> alreadySeen;
@@ -44,44 +38,11 @@ class swift::ClangModuleDependenciesCacheImpl {
   DependencyScanningTool tool;
 
   ClangModuleDependenciesCacheImpl()
-      : importHackFileCache(), service(ScanningMode::DependencyDirectivesScan,
-                                       ScanningOutputFormat::Full,
-                                       clang::CASOptions(), nullptr, nullptr),
+      : service(ScanningMode::DependencyDirectivesScan,
+                ScanningOutputFormat::Full, clang::CASOptions(), nullptr, nullptr),
         tool(service) {}
-  ~ClangModuleDependenciesCacheImpl();
-
-  /// Retrieve the name of the file used for the "import hack" that is
-  /// used to scan the dependencies of a Clang module.
-  llvm::ErrorOr<StringRef> getImportHackFile(StringRef moduleName);
 };
 
-ClangModuleDependenciesCacheImpl::~ClangModuleDependenciesCacheImpl() {
-  if (!importHackFileCache.empty()) {
-    for (auto& it: importHackFileCache) {
-      llvm::sys::fs::remove(it.second);
-    }
-  }
-}
-
-llvm::ErrorOr<StringRef> ClangModuleDependenciesCacheImpl::getImportHackFile(StringRef moduleName) {
-  auto cacheIt = importHackFileCache.find(moduleName.str());
-  if (cacheIt != importHackFileCache.end())
-    return cacheIt->second;
-
-  // Create a temporary file.
-  int resultFD;
-  SmallString<128> resultPath;
-  if (auto error = llvm::sys::fs::createTemporaryFile(
-          "import-hack-" + moduleName.str(), "c", resultFD, resultPath))
-    return error;
-
-  llvm::raw_fd_ostream out(resultFD, /*shouldClose=*/true);
-  out << "#pragma clang module import " << moduleName.str() << ";\n";
-  llvm::sys::RemoveFileOnSignal(resultPath);
-  importHackFileCache.insert(std::make_pair(moduleName, resultPath.str().str()));
-  return importHackFileCache[moduleName];
-}
-
 // Add search paths.
 // Note: This is handled differently for the Clang importer itself, which
 // adds search paths to Clang's data structures rather than to its
@@ -103,7 +64,7 @@ static void addSearchPathInvocationArguments(
 /// Create the command line for Clang dependency scanning.
 static std::vector<std::string> getClangDepScanningInvocationArguments(
     ASTContext &ctx,
-    StringRef sourceFileName) {
+    Optional<StringRef> sourceFileName = None) {
   std::vector<std::string> commandLineArgs;
 
   // Form the basic command line.
@@ -116,7 +77,10 @@ static std::vector<std::string> getClangDepScanningInvocationArguments(
       commandLineArgs.begin(), commandLineArgs.end(),
       "<swift-imported-modules>");
   assert(sourceFilePos != commandLineArgs.end());
-  *sourceFilePos = sourceFileName.str();
+  if (sourceFileName.hasValue())
+    *sourceFilePos = sourceFileName->str();
+  else
+    commandLineArgs.erase(sourceFilePos);
 
   // HACK! Drop the -fmodule-format= argument and the one that
   // precedes it.
@@ -140,18 +104,6 @@ static std::vector<std::string> getClangDepScanningInvocationArguments(
     *syntaxOnlyPos = "-c";
   }
 
-  // HACK: Stolen from ClangScanDeps.cpp
-  commandLineArgs.push_back("-o");
-  commandLineArgs.push_back("/dev/null");
-  commandLineArgs.push_back("-M");
-  commandLineArgs.push_back("-MT");
-  commandLineArgs.push_back("import-hack.o");
-  commandLineArgs.push_back("-Xclang");
-  commandLineArgs.push_back("-Eonly");
-  commandLineArgs.push_back("-Xclang");
-  commandLineArgs.push_back("-sys-header-deps");
-  commandLineArgs.push_back("-Wno-error");
-
   return commandLineArgs;
 }
 
@@ -323,16 +275,9 @@ Optional<ModuleDependencies> ClangImporter::getModuleDependencies(
   // Retrieve or create the shared state.
   auto clangImpl = getOrCreateClangImpl(cache);
 
-  // HACK! Replace the module import buffer name with the source file hack.
-  auto importHackFile = clangImpl->getImportHackFile(moduleName);
-  if (!importHackFile) {
-    // FIXME: Emit a diagnostic here.
-    return None;
-  }
-
   // Determine the command-line arguments for dependency scanning.
   std::vector<std::string> commandLineArgs =
-    getClangDepScanningInvocationArguments(ctx, *importHackFile);
+    getClangDepScanningInvocationArguments(ctx);
   // The Swift compiler does not have a concept of a working directory.
   // It is instead handled by the Swift driver by resolving relative paths
   // according to the driver's notion of a working directory. On the other hand,
@@ -354,7 +299,7 @@ Optional<ModuleDependencies> ClangImporter::getModuleDependencies(
   }
 
   auto clangDependencies = clangImpl->tool.getFullDependencies(
-      commandLineArgs, workingDir, clangImpl->alreadySeen);
+      commandLineArgs, workingDir, clangImpl->alreadySeen, moduleName);
   if (!clangDependencies) {
     auto errorStr = toString(clangDependencies.takeError());
     // We ignore the "module 'foo' not found" error, the Swift dependency
@@ -407,7 +352,7 @@ bool ClangImporter::addBridgingHeaderDependencies(
 
   // Determine the command-line arguments for dependency scanning.
   std::vector<std::string> commandLineArgs =
-    getClangDepScanningInvocationArguments(ctx, bridgingHeader);
+    getClangDepScanningInvocationArguments(ctx, StringRef(bridgingHeader));
   std::string workingDir =
       ctx.SourceMgr.getFileSystem()->getCurrentWorkingDirectory().get();