Revert "[clang] Convert OptionalFileEntryRefDegradesToFileEntryPtr to std::optional"

This reverts commit 8f0df9f3bbc6d7f3d5cbfd955c5ee4404c53a75d.

The Optional*RefDegradesTo*EntryPtr types want to keep the same size as
the underlying type, which std::optional doesn't guarantee. For use with
llvm::Optional, they define their own storage class, and there is no way
to do that in std::optional.

On top of that, that commit broke builds with older GCCs, where
std::optional was not trivially copyable (static_assert in the clang
sources was failing).

2 files changed, 3 insertions, 4 deletions

diff --git a/clang/lib/Basic/FileManager.cpp b/clang/lib/Basic/FileManager.cpp
index 1d96093..4fefbaa 100644
--- a/clang/lib/Basic/FileManager.cpp
+++ b/clang/lib/Basic/FileManager.cpp
@@ -471,7 +471,7 @@ FileEntryRef FileManager::getVirtualFileRef(StringRef Filename, off_t Size,
   return FileEntryRef(NamedFileEnt);
 }
 
-std::optional<FileEntryRef> FileManager::getBypassFile(FileEntryRef VF) {
+llvm::Optional<FileEntryRef> 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))
diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index c9312c6..8eca151 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -38,7 +38,6 @@
 #include <cstddef>
 #include <cstdint>
 #include <memory>
-#include <optional>
 #include <tuple>
 #include <utility>
 #include <vector>
@@ -713,10 +712,10 @@ void SourceManager::overrideFileContents(const FileEntry *SourceFile,
     Pair.first->second = NewFile;
 }
 
-std::optional<FileEntryRef>
+Optional<FileEntryRef>
 SourceManager::bypassFileContentsOverride(FileEntryRef File) {
   assert(isFileOverridden(&File.getFileEntry()));
-  std::optional<FileEntryRef> BypassFile = FileMgr.getBypassFile(File);
+  llvm::Optional<FileEntryRef> BypassFile = FileMgr.getBypassFile(File);
 
   // If the file can't be found in the FS, give up.
   if (!BypassFile)