[clang] NFCI: Use `FileEntryRef` in `ModuleMapCallbacks`

[jansvoboda11]

Summary

This patch removes path hackery from ModuleMapCallbacks by adopting FileEntryRef. No functional change intended.

[benlangmuir]

Nice simplification!

clang/include/clang/Lex/ModuleMap.h

71

Doc comment needs update

clang/include/clang/Lex/ModuleMap.h

public:
 
   /// Called when a header is added during module map parsing.
   ///
   /// \param Filename The header file itself.
   virtual void moduleMapAddHeader(StringRef Filename) {}
 
   /// Called when an umbrella header is added during module map parsing.
   ///
-  /// \param FileMgr FileManager instance
   /// \param Header The umbrella header to collect.
-  virtual void moduleMapAddUmbrellaHeader(FileManager *FileMgr,
-                                          const FileEntry *Header) {}
+  virtual void moduleMapAddUmbrellaHeader(FileEntryRef Header) {}
 };
 
 class ModuleMap {
   SourceManager &SourceMgr;
   DiagnosticsEngine &Diags;
   const LangOptions &LangOpts;
   const TargetInfo *Target;
   HeaderSearch &HeaderInfo;

clang/lib/Frontend/ModuleDependencyCollector.cpp

struct ModuleDependencyMMCallbacks : public ModuleMapCallbacks {
   ModuleDependencyCollector &Collector;
   ModuleDependencyMMCallbacks(ModuleDependencyCollector &Collector)
       : Collector(Collector) {}
 
   void moduleMapAddHeader(StringRef HeaderPath) override {
     if (llvm::sys::path::is_absolute(HeaderPath))
       Collector.addFile(HeaderPath);
   }
-  void moduleMapAddUmbrellaHeader(FileManager *FileMgr,
-                                  const FileEntry *Header) override {
-    StringRef HeaderFilename = Header->getName();
-    moduleMapAddHeader(HeaderFilename);
-    // The FileManager can find and cache the symbolic link for a framework
-    // header before its real path, this means a module can have some of its
-    // headers to use other paths. Although this is usually not a problem, it's
-    // inconsistent, and not collecting the original path header leads to
-    // umbrella clashes while rebuilding modules in the crash reproducer. For
-    // example:
-    //    ApplicationServices.framework/Frameworks/ImageIO.framework/ImageIO.h
-    // instead of:
-    //    ImageIO.framework/ImageIO.h
-    //
-    // FIXME: this shouldn't be necessary once we have FileName instances
-    // around instead of FileEntry ones. For now, make sure we collect all
-    // that we need for the reproducer to work correctly.
-    StringRef UmbreallDirFromHeader =
-        llvm::sys::path::parent_path(HeaderFilename);
-    StringRef UmbrellaDir = Header->getDir()->getName();
-    if (!UmbrellaDir.equals(UmbreallDirFromHeader)) {
-      SmallString<128> AltHeaderFilename;
-      llvm::sys::path::append(AltHeaderFilename, UmbrellaDir,
-                              llvm::sys::path::filename(HeaderFilename));
-      if (FileMgr->getFile(AltHeaderFilename))
-        moduleMapAddHeader(AltHeaderFilename);
-    }
+  void moduleMapAddUmbrellaHeader(FileEntryRef Header) override {
+    moduleMapAddHeader(Header.getNameAsRequested());
   }
 };
 
-}
+} // namespace
 
 void ModuleDependencyCollector::attachToASTReader(ASTReader &R) {
   R.addListener(
       std::make_unique<ModuleDependencyListener>(*this, R.getFileManager()));
 }
 
 void ModuleDependencyCollector::attachToPreprocessor(Preprocessor &PP) {
   PP.addPPCallbacks(std::make_unique<ModuleDependencyPPCallbacks>(

clang/lib/Lex/ModuleMap.cpp

void ModuleMap::setUmbrellaHeaderAsWritten(
   Mod->Umbrella = &UmbrellaHeader.getMapEntry();
   Mod->UmbrellaAsWritten = NameAsWritten.str();
   Mod->UmbrellaRelativeToRootModuleDirectory =
       PathRelativeToRootModuleDirectory.str();
   UmbrellaDirs[UmbrellaHeader.getDir()] = Mod;
 
   // Notify callbacks that we just added a new header.
   for (const auto &Cb : Callbacks)
-    Cb->moduleMapAddUmbrellaHeader(&SourceMgr.getFileManager(), UmbrellaHeader);
+    Cb->moduleMapAddUmbrellaHeader(UmbrellaHeader);
 }
 
 void ModuleMap::setUmbrellaDirAsWritten(
     Module *Mod, DirectoryEntryRef UmbrellaDir, const Twine &NameAsWritten,
     const Twine &PathRelativeToRootModuleDirectory) {
   Mod->Umbrella = &UmbrellaDir.getMapEntry();
   Mod->UmbrellaAsWritten = NameAsWritten.str();
   Mod->UmbrellaRelativeToRootModuleDirectory =