Separate dependency tracking from Make-style .d file generation.

This refactoring is groundwork for saving the cross-module dependencies
in the swiftdeps files as well, so that we know to rebuild files if an
outside file changes (such as a bridging header, another framework's
headers, or another framework's swiftmodule).

Part of rdar://problem/19270920

Swift SVN r24258

include/swift/AST/ModuleLoader.h

@@ -20,6 +20,7 @@
 #include "swift/AST/Identifier.h"
 #include "swift/Basic/LLVM.h"
 #include "swift/Basic/SourceLoc.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/TinyPtrVector.h"
 
 namespace swift {
@@ -31,13 +32,28 @@ class NominalTypeDecl;
 
 enum class KnownProtocolKind : uint8_t;
 
+/// Records dependencies on files outside of the current module.
 class DependencyTracker {
-  virtual void anchor();
-protected:
-  DependencyTracker() = default;
+  llvm::SetVector<std::string, std::vector<std::string>> paths;
+
 public:
-  virtual ~DependencyTracker() = default;
-  virtual void addDependency(StringRef file) {}
+  /// Adds a file as a dependency.
+  ///
+  /// The contents of \p file are taken literally, and should be appropriate
+  /// for appearing in a list of dependencies suitable for tooling like Make.
+  /// No path canonicalization is done.
+  void addDependency(StringRef file) {
+    paths.insert(file);
+  }
+
+  /// Fetches the list of dependencies.
+  ArrayRef<std::string> getDependencies() const {
+    if (paths.empty())
+      return None;
+    assert((&paths[0]) + (paths.size() - 1) == &paths.back() &&
+           "elements not stored contiguously");
+    return llvm::makeArrayRef(&paths[0], paths.size());
+  }
 };
 
 /// \brief Abstract interface that loads named modules into the AST.

include/swift/Frontend/DependencyFileGenerator.h

@@ -1,34 +0,0 @@
-//===- DependencyFileGenerator.h - .d file generation -----------*- C++ -*-===//
-//
-// This source file is part of the Swift.org open source project
-//
-// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
-// Licensed under Apache License v2.0 with Runtime Library Exception
-//
-// See http://swift.org/LICENSE.txt for license information
-// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef SWIFT_FRONTEND_DEPENDENCYFILEGENERATOR_H
-#define SWIFT_FRONTEND_DEPENDENCYFILEGENERATOR_H
-
-#include "swift/AST/ModuleLoader.h"
-#include "swift/Basic/LLVM.h"
-#include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/StringSet.h"
-#include <vector>
-
-namespace swift {
-  class DependencyFileGenerator : public DependencyTracker {
-    std::vector<std::string> targets;
-    llvm::SetVector<std::string, std::vector<std::string>> paths;
-  public:
-    virtual void addDependency(StringRef file) override;
-
-    void addTarget(StringRef targetName);
-    void writeToStream(llvm::raw_ostream &os) const;
-  };
-}
-
-#endif

lib/AST/ASTContext.cpp

@@ -39,7 +39,6 @@ using namespace swift;
 
 LazyResolver::~LazyResolver() = default;
 void ModuleLoader::anchor() {}
-void DependencyTracker::anchor() {}
 
 llvm::StringRef swift::getProtocolName(KnownProtocolKind kind) {
   switch (kind) {

lib/Frontend/CMakeLists.txt

@@ -1,6 +1,5 @@
 add_swift_library(swiftFrontend
   CompilerInvocation.cpp
-  DependencyFileGenerator.cpp
   DiagnosticVerifier.cpp
   Frontend.cpp
   FrontendOptions.cpp

lib/Frontend/DependencyFileGenerator.cpp

@@ -1,57 +0,0 @@
-//===- DependencyFileGenerator.cpp - .d file generation -------------------===//
-//
-// This source file is part of the Swift.org open source project
-//
-// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
-// Licensed under Apache License v2.0 with Runtime Library Exception
-//
-// See http://swift.org/LICENSE.txt for license information
-// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
-//
-//===----------------------------------------------------------------------===//
-
-#include "swift/Frontend/DependencyFileGenerator.h"
-#include "llvm/ADT/SmallString.h"
-#include "llvm/Support/raw_ostream.h"
-
-using namespace swift;
-
-void DependencyFileGenerator::addDependency(StringRef file) {
-  paths.insert(file);
-}
-
-void DependencyFileGenerator::addTarget(StringRef targetName) {
-  if (!targetName.empty())
-    targets.push_back(targetName);
-}
-
-void DependencyFileGenerator::writeToStream(llvm::raw_ostream &os) const {
-  // Declare a helper for escaping file names for use in Makefiles.
-  llvm::SmallString<256> pathBuf;
-  auto escape = [&](StringRef raw) -> StringRef {
-    pathBuf.clear();
-    
-    static const char badChars[] = " $#:\n";
-    size_t prev = 0;
-    for (auto index = raw.find_first_of(badChars); index != StringRef::npos;
-         index = raw.find_first_of(badChars, index+1)) {
-      pathBuf.append(raw.slice(prev, index));
-      if (raw[index] == '$')
-        pathBuf.push_back('$');
-      else
-        pathBuf.push_back('\\');
-      prev = index;
-    }
-    pathBuf.append(raw.substr(prev));
-    return pathBuf;
-  };
-
-  // FIXME: Xcode can't currently handle multiple targets in a single
-  // dependency line.
-  for (StringRef targetName : targets) {
-    os << targetName << " :";
-    for (StringRef path : paths)
-      os << ' ' << escape(path);
-    os << '\n';
-  }
-}

tools/driver/frontend_main.cpp

@@ -25,7 +25,6 @@
 #include "swift/AST/ReferencedNameTracker.h"
 #include "swift/Basic/Fallthrough.h"
 #include "swift/Basic/SourceManager.h"
-#include "swift/Frontend/DependencyFileGenerator.h"
 #include "swift/Frontend/DiagnosticVerifier.h"
 #include "swift/Frontend/Frontend.h"
 #include "swift/Frontend/PrintingDiagnosticConsumer.h"
@@ -57,23 +56,54 @@ static std::string displayName(StringRef MainExecutablePath) {
 }
 
 /// Emits a Make-style dependencies file.
-static bool emitMakeDependencies(DiagnosticEngine &Diags,
-                                 DependencyFileGenerator &DFG,
+static bool emitMakeDependencies(DiagnosticEngine &diags,
+                                 DependencyTracker &depTracker,
                                  const FrontendOptions &opts) {
-  opts.forAllOutputPaths([&DFG](StringRef target) { DFG.addTarget(target); });
-
   std::error_code EC;
   llvm::raw_fd_ostream out(opts.DependenciesFilePath, EC,
                            llvm::sys::fs::F_None);
 
   if (out.has_error() || EC) {
-    Diags.diagnose(SourceLoc(), diag::error_opening_output,
+    diags.diagnose(SourceLoc(), diag::error_opening_output,
                    opts.DependenciesFilePath, EC.message());
     out.clear_error();
     return true;
   }
 
-  DFG.writeToStream(out);
+  // Declare a helper for escaping file names for use in Makefiles.
+  llvm::SmallString<256> pathBuf;
+  auto escape = [&](StringRef raw) -> StringRef {
+    pathBuf.clear();
+
+    static const char badChars[] = " $#:\n";
+    size_t prev = 0;
+    for (auto index = raw.find_first_of(badChars); index != StringRef::npos;
+         index = raw.find_first_of(badChars, index+1)) {
+      pathBuf.append(raw.slice(prev, index));
+      if (raw[index] == '$')
+        pathBuf.push_back('$');
+      else
+        pathBuf.push_back('\\');
+      prev = index;
+    }
+    pathBuf.append(raw.substr(prev));
+    return pathBuf;
+  };
+
+  // FIXME: Xcode can't currently handle multiple targets in a single
+  // dependency line.
+  opts.forAllOutputPaths([&](StringRef targetName) {
+    out << targetName << " :";
+    // Print dependencies we've picked up during compilation.
+    for (StringRef path : depTracker.getDependencies())
+      out << ' ' << escape(path);
+    // Also include all other files in the module. Make-style dependencies
+    // need to be conservative!
+    for (StringRef path : opts.InputFilenames)
+      out << ' ' << escape(path);
+    out << '\n';
+  });
+
   return false;
 }
 
@@ -342,10 +372,8 @@ static bool performCompile(CompilerInstance &Instance,
   if (opts.PrintClangStats && Context.getClangModuleLoader())
     Context.getClangModuleLoader()->printStatistics();
 
-  if (DependencyTracker *DT = Instance.getDependencyTracker()) {
-    auto &DFG = *static_cast<DependencyFileGenerator*>(DT);
-    (void)emitMakeDependencies(Context.Diags, DFG, opts);
-  }
+  if (DependencyTracker *DT = Instance.getDependencyTracker())
+    (void)emitMakeDependencies(Context.Diags, *DT, opts);
 
   if (shouldTrackReferences)
     emitReferenceDependencies(Context.Diags, Instance.getPrimarySourceFile(),
@@ -594,9 +622,9 @@ int frontend_main(ArrayRef<const char *>Args,
     enableDiagnosticVerifier(Instance.getSourceMgr());
   }
 
-  DependencyFileGenerator DFG;
+  DependencyTracker depTracker;
   if (!Invocation.getFrontendOptions().DependenciesFilePath.empty())
-    Instance.setDependencyTracker(&DFG);
+    Instance.setDependencyTracker(&depTracker);
 
   if (Instance.setup(Invocation)) {
     return 1;