Revert "Lex: Migrate HeaderSearch::LoadedModuleMaps to FileEntryRef"

This reverts commit a40db5502b2515a6f2f1676b5d7a655ae0f41179.
and follow-up d636b881bb9214938973098a012fad453082c444

Somewhat speculative, likely broke check-clang on Windows:
https://reviews.llvm.org/D92975#2453482

3 files changed, 35 insertions, 32 deletions

diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
index d3891eb..2317873 100644
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -432,7 +432,7 @@ static bool loadModuleMapForModuleBuild(CompilerInstance &CI, bool IsSystem,
 
   // Map the current input to a file.
   FileID ModuleMapID = SrcMgr.getMainFileID();
-  Optional<FileEntryRef> ModuleMap = SrcMgr.getFileEntryRefForID(ModuleMapID);
+  const FileEntry *ModuleMap = SrcMgr.getFileEntryForID(ModuleMapID);
 
   // If the module map is preprocessed, handle the initial line marker;
   // line directives are not part of the module map syntax in general.
@@ -445,7 +445,7 @@ static bool loadModuleMapForModuleBuild(CompilerInstance &CI, bool IsSystem,
   }
 
   // Load the module map file.
-  if (HS.loadModuleMapFile(*ModuleMap, IsSystem, ModuleMapID, &Offset,
+  if (HS.loadModuleMapFile(ModuleMap, IsSystem, ModuleMapID, &Offset,
                            PresumedModuleMapFile))
     return true;
 
@@ -807,7 +807,7 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
 
   // If we were asked to load any module map files, do so now.
   for (const auto &Filename : CI.getFrontendOpts().ModuleMapFiles) {
-    if (auto File = CI.getFileManager().getOptionalFileRef(Filename))
+    if (auto File = CI.getFileManager().getFile(Filename))
       CI.getPreprocessor().getHeaderSearchInfo().loadModuleMapFile(
           *File, /*IsSystem*/false);
     else
diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 3cc8ce4..99c92e9 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -1499,20 +1499,22 @@ bool HeaderSearch::findUsableModuleForFrameworkHeader(
   return true;
 }
 
-static Optional<FileEntryRef> getPrivateModuleMap(FileEntryRef File,
-                                                  FileManager &FileMgr) {
-  StringRef Filename = llvm::sys::path::filename(File.getName());
-  SmallString<128> PrivateFilename(File.getDir().getName());
+static const FileEntry *getPrivateModuleMap(const FileEntry *File,
+                                            FileManager &FileMgr) {
+  StringRef Filename = llvm::sys::path::filename(File->getName());
+  SmallString<128>  PrivateFilename(File->getDir()->getName());
   if (Filename == "module.map")
     llvm::sys::path::append(PrivateFilename, "module_private.map");
   else if (Filename == "module.modulemap")
     llvm::sys::path::append(PrivateFilename, "module.private.modulemap");
   else
-    return None;
-  return FileMgr.getOptionalFileRef(PrivateFilename);
+    return nullptr;
+  if (auto File = FileMgr.getFile(PrivateFilename))
+    return *File;
+  return nullptr;
 }
 
-bool HeaderSearch::loadModuleMapFile(FileEntryRef File, bool IsSystem,
+bool HeaderSearch::loadModuleMapFile(const FileEntry *File, bool IsSystem,
                                      FileID ID, unsigned *Offset,
                                      StringRef OriginalModuleMapFile) {
   // Find the directory for the module. For frameworks, that may require going
@@ -1534,7 +1536,7 @@ bool HeaderSearch::loadModuleMapFile(FileEntryRef File, bool IsSystem,
         Dir = FakeFile->getDir();
       }
     } else {
-      Dir = File.getDir();
+      Dir = File->getDir();
     }
 
     StringRef DirName(Dir->getName());
@@ -1561,9 +1563,11 @@ bool HeaderSearch::loadModuleMapFile(FileEntryRef File, bool IsSystem,
 }
 
 HeaderSearch::LoadModuleMapResult
-HeaderSearch::loadModuleMapFileImpl(FileEntryRef File, bool IsSystem,
+HeaderSearch::loadModuleMapFileImpl(const FileEntry *File, bool IsSystem,
                                     const DirectoryEntry *Dir, FileID ID,
                                     unsigned *Offset) {
+  assert(File && "expected FileEntry");
+
   // Check whether we've already loaded this module map, and mark it as being
   // loaded in case we recursively try to load it from itself.
   auto AddResult = LoadedModuleMaps.insert(std::make_pair(File, true));
@@ -1576,8 +1580,8 @@ HeaderSearch::loadModuleMapFileImpl(FileEntryRef File, bool IsSystem,
   }
 
   // Try to load a corresponding private module map.
-  if (Optional<FileEntryRef> PMMFile = getPrivateModuleMap(File, FileMgr)) {
-    if (ModMap.parseModuleMapFile(*PMMFile, IsSystem, Dir)) {
+  if (const FileEntry *PMMFile = getPrivateModuleMap(File, FileMgr)) {
+    if (ModMap.parseModuleMapFile(PMMFile, IsSystem, Dir)) {
       LoadedModuleMaps[File] = false;
       return LMM_InvalidModuleMap;
     }
@@ -1587,24 +1591,24 @@ HeaderSearch::loadModuleMapFileImpl(FileEntryRef File, bool IsSystem,
   return LMM_NewlyLoaded;
 }
 
-Optional<FileEntryRef>
+const FileEntry *
 HeaderSearch::lookupModuleMapFile(const DirectoryEntry *Dir, bool IsFramework) {
   if (!HSOpts->ImplicitModuleMaps)
-    return None;
+    return nullptr;
   // For frameworks, the preferred spelling is Modules/module.modulemap, but
   // module.map at the framework root is also accepted.
   SmallString<128> ModuleMapFileName(Dir->getName());
   if (IsFramework)
     llvm::sys::path::append(ModuleMapFileName, "Modules");
   llvm::sys::path::append(ModuleMapFileName, "module.modulemap");
-  if (auto F = FileMgr.getOptionalFileRef(ModuleMapFileName))
-    return F;
+  if (auto F = FileMgr.getFile(ModuleMapFileName))
+    return *F;
 
   // Continue to allow module.map
   ModuleMapFileName = Dir->getName();
   llvm::sys::path::append(ModuleMapFileName, "module.map");
-  if (auto F = FileMgr.getOptionalFileRef(ModuleMapFileName))
-    return F;
+  if (auto F = FileMgr.getFile(ModuleMapFileName))
+    return *F;
 
   // For frameworks, allow to have a private module map with a preferred
   // spelling when a public module map is absent.
@@ -1612,10 +1616,10 @@ HeaderSearch::lookupModuleMapFile(const DirectoryEntry *Dir, bool IsFramework) {
     ModuleMapFileName = Dir->getName();
     llvm::sys::path::append(ModuleMapFileName, "Modules",
                             "module.private.modulemap");
-    if (auto F = FileMgr.getOptionalFileRef(ModuleMapFileName))
-      return F;
+    if (auto F = FileMgr.getFile(ModuleMapFileName))
+      return *F;
   }
-  return None;
+  return nullptr;
 }
 
 Module *HeaderSearch::loadFrameworkModule(StringRef Name,
@@ -1659,10 +1663,9 @@ HeaderSearch::loadModuleMapFile(const DirectoryEntry *Dir, bool IsSystem,
   if (KnownDir != DirectoryHasModuleMap.end())
     return KnownDir->second ? LMM_AlreadyLoaded : LMM_InvalidModuleMap;
 
-  if (Optional<FileEntryRef> ModuleMapFile =
-          lookupModuleMapFile(Dir, IsFramework)) {
+  if (const FileEntry *ModuleMapFile = lookupModuleMapFile(Dir, IsFramework)) {
     LoadModuleMapResult Result =
-        loadModuleMapFileImpl(*ModuleMapFile, IsSystem, Dir);
+        loadModuleMapFileImpl(ModuleMapFile, IsSystem, Dir);
     // Add Dir explicitly in case ModuleMapFile is in a subdirectory.
     // E.g. Foo.framework/Modules/module.modulemap
     //      ^Dir                  ^ModuleMapFile
diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index 152fc9e..bbda1f1 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -973,9 +973,9 @@ Module *ModuleMap::inferFrameworkModule(const DirectoryEntry *FrameworkDir,
           // We haven't looked here before. Load a module map, if there is
           // one.
           bool IsFrameworkDir = Parent.endswith(".framework");
-          if (Optional<FileEntryRef> ModMapFile =
-                  HeaderInfo.lookupModuleMapFile(*ParentDir, IsFrameworkDir)) {
-            parseModuleMapFile(*ModMapFile, Attrs.IsSystem, *ParentDir);
+          if (const FileEntry *ModMapFile =
+                HeaderInfo.lookupModuleMapFile(*ParentDir, IsFrameworkDir)) {
+            parseModuleMapFile(ModMapFile, Attrs.IsSystem, *ParentDir);
             inferred = InferredDirectories.find(*ParentDir);
           }
 
@@ -2163,12 +2163,12 @@ void ModuleMapParser::parseExternModuleDecl() {
     llvm::sys::path::append(ModuleMapFileName, FileName);
     FileNameRef = ModuleMapFileName;
   }
-  if (auto File = SourceMgr.getFileManager().getOptionalFileRef(FileNameRef))
+  if (auto File = SourceMgr.getFileManager().getFile(FileNameRef))
     Map.parseModuleMapFile(
         *File, /*IsSystem=*/false,
         Map.HeaderInfo.getHeaderSearchOpts().ModuleMapFileHomeIsCwd
             ? Directory
-            : File->getDir(),
+            : (*File)->getDir(),
         FileID(), nullptr, ExternLoc);
 }
 
@@ -2984,7 +2984,7 @@ bool ModuleMapParser::parseModuleMapFile() {
   } while (true);
 }
 
-bool ModuleMap::parseModuleMapFile(FileEntryRef File, bool IsSystem,
+bool ModuleMap::parseModuleMapFile(const FileEntry *File, bool IsSystem,
                                    const DirectoryEntry *Dir, FileID ID,
                                    unsigned *Offset,
                                    SourceLocation ExternModuleLoc) {