1 files changed, 8 insertions, 32 deletions

diff --git a/clang/lib/Basic/FileManager.cpp b/clang/lib/Basic/FileManager.cpp
index b66780a1d1d1..e8d0f20019eb 100644
--- a/clang/lib/Basic/FileManager.cpp
+++ b/clang/lib/Basic/FileManager.cpp
@@ -31,6 +31,7 @@
 #include <climits>
 #include <cstdint>
 #include <cstdlib>
+#include <optional>
 #include <string>
 #include <utility>
 
@@ -123,7 +124,7 @@ FileManager::getDirectoryRef(StringRef DirName, bool CacheFailure) {
       DirName != llvm::sys::path::root_path(DirName) &&
       llvm::sys::path::is_separator(DirName.back()))
     DirName = DirName.substr(0, DirName.size()-1);
-  Optional<std::string> DirNameStr;
+  std::optional<std::string> DirNameStr;
   if (is_style_windows(llvm::sys::path::Style::native)) {
     // Fixing a problem with "clang C:test.c" on Windows.
     // Stat("C:") does not recognize "C:" as a valid directory
@@ -212,13 +213,7 @@ FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) {
     if (!SeenFileInsertResult.first->second)
       return llvm::errorCodeToError(
           SeenFileInsertResult.first->second.getError());
-    // Construct and return and FileEntryRef, unless it's a redirect to another
-    // filename.
-    FileEntryRef::MapValue Value = *SeenFileInsertResult.first->second;
-    if (LLVM_LIKELY(Value.V.is<FileEntry *>()))
-      return FileEntryRef(*SeenFileInsertResult.first);
-    return FileEntryRef(*reinterpret_cast<const FileEntryRef::MapEntry *>(
-        Value.V.get<const void *>()));
+    return FileEntryRef(*SeenFileInsertResult.first);
   }
 
   // We've not seen this before. Fill it in.
@@ -274,8 +269,8 @@ FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) {
   if (!UFE)
     UFE = new (FilesAlloc.Allocate()) FileEntry();
 
-  if (Status.getName() == Filename) {
-    // The name matches. Set the FileEntry.
+  if (!Status.ExposesExternalVFSPath || Status.getName() == Filename) {
+    // Use the requested name. Set the FileEntry.
     NamedFileEnt->second = FileEntryRef::MapValue(*UFE, DirInfo);
   } else {
     // Name mismatch. We need a redirect. First grab the actual entry we want
@@ -292,25 +287,9 @@ FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) {
     // filesystems behave and confuses parts of clang expect to see the
     // name-as-accessed on the \a FileEntryRef.
     //
-    // Further, it isn't *just* external names, but will also give back absolute
-    // paths when a relative path was requested - the check is comparing the
-    // name from the status, which is passed an absolute path resolved from the
-    // current working directory. `clang-apply-replacements` appears to depend
-    // on this behaviour, though it's adjusting the working directory, which is
-    // definitely not supported. Once that's fixed this hack should be able to
-    // be narrowed to only when there's an externally mapped name given back.
-    //
     // A potential plan to remove this is as follows -
-    //   - Add API to determine if the name has been rewritten by the VFS.
-    //   - Fix `clang-apply-replacements` to pass down the absolute path rather
-    //     than changing the CWD. Narrow this hack down to just externally
-    //     mapped paths.
-    //   - Expose the requested filename. One possibility would be to allow
-    //     redirection-FileEntryRefs to be returned, rather than returning
-    //     the pointed-at-FileEntryRef, and customizing `getName()` to look
-    //     through the indirection.
     //   - Update callers such as `HeaderSearch::findUsableModuleForHeader()`
-    //     to explicitly use the requested filename rather than just using
+    //     to explicitly use the `getNameAsRequested()` rather than just using
     //     `getName()`.
     //   - Add a `FileManager::getExternalPath` API for explicitly getting the
     //     remapped external filename when there is one available. Adopt it in
@@ -341,9 +320,6 @@ FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) {
     // Cache the redirection in the previously-inserted entry, still available
     // in the tentative return value.
     NamedFileEnt->second = FileEntryRef::MapValue(Redirection);
-
-    // Fix the tentative return value.
-    NamedFileEnt = &Redirection;
   }
 
   FileEntryRef ReturnedRef(*NamedFileEnt);
@@ -495,11 +471,11 @@ FileEntryRef FileManager::getVirtualFileRef(StringRef Filename, off_t Size,
   return FileEntryRef(NamedFileEnt);
 }
 
-llvm::Optional<FileEntryRef> FileManager::getBypassFile(FileEntryRef VF) {
+OptionalFileEntryRef FileManager::getBypassFile(FileEntryRef VF) {
   // Stat of the file and return nullptr if it doesn't exist.
   llvm::vfs::Status Status;
   if (getStatValue(VF.getName(), Status, /*isFile=*/true, /*F=*/nullptr))
-    return None;
+    return std::nullopt;
 
   if (!SeenBypassFileEntries)
     SeenBypassFileEntries = std::make_unique<