4 files changed, 23 insertions, 11 deletions
diff --git a/clang/lib/Basic/FileManager.cpp b/clang/lib/Basic/FileManager.cpp
index 6097b85..27075ce 100644
--- a/clang/lib/Basic/FileManager.cpp
+++ b/clang/lib/Basic/FileManager.cpp
@@ -530,7 +530,7 @@ void FileManager::fillRealPathName(FileEntry *UFE, llvm::StringRef FileName) {
 
 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
 FileManager::getBufferForFile(FileEntryRef FE, bool isVolatile,
-                              bool RequiresNullTerminator,
+                              bool RequiresNullTerminator, bool IsText,
                               std::optional<int64_t> MaybeLimit) {
   const FileEntry *Entry = &FE.getFileEntry();
   // If the content is living on the file entry, return a reference to it.
@@ -558,21 +558,21 @@ FileManager::getBufferForFile(FileEntryRef FE, bool isVolatile,
 
   // Otherwise, open the file.
   return getBufferForFileImpl(Filename, FileSize, isVolatile,
-                              RequiresNullTerminator);
+                              RequiresNullTerminator, IsText);
 }
 
 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
 FileManager::getBufferForFileImpl(StringRef Filename, int64_t FileSize,
-                                  bool isVolatile,
-                                  bool RequiresNullTerminator) const {
+                                  bool isVolatile, bool RequiresNullTerminator,
+                                  bool IsText) const {
   if (FileSystemOpts.WorkingDir.empty())
     return FS->getBufferForFile(Filename, FileSize, RequiresNullTerminator,
-                                isVolatile);
+                                isVolatile, IsText);
 
   SmallString<128> FilePath(Filename);
   FixupRelativePath(FilePath);
   return FS->getBufferForFile(FilePath, FileSize, RequiresNullTerminator,
-                              isVolatile);
+                              isVolatile, IsText);
 }
 
 /// getStatValue - Get the 'stat' information for the specified path,
diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index 65a8a72..fe3aff7 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -121,8 +121,18 @@ ContentCache::getBufferOrNone(DiagnosticsEngine &Diag, FileManager &FM,
   // Start with the assumption that the buffer is invalid to simplify early
   // return paths.
   IsBufferInvalid = true;
-
-  auto BufferOrError = FM.getBufferForFile(*ContentsEntry, IsFileVolatile);
+  bool IsText = false;
+
+#ifdef __MVS__
+  // If the file is tagged with a text ccsid, it may require autoconversion.
+  llvm::ErrorOr<bool> IsFileText =
+      llvm::iszOSTextFile(ContentsEntry->getName().data());
+  if (IsFileText)
+    IsText = *IsFileText;
+#endif
+
+  auto BufferOrError = FM.getBufferForFile(
+      *ContentsEntry, IsFileVolatile, /*RequiresNullTerminator=*/true, IsText);
 
   // If we were unable to open the file, then we are in an inconsistent
   // situation where the content cache referenced a file which no longer
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 7efcc81..ad0551e 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -5317,7 +5317,8 @@ std::string ASTReader::getOriginalSourceFile(
     const PCHContainerReader &PCHContainerRdr, DiagnosticsEngine &Diags) {
   // Open the AST file.
   auto Buffer = FileMgr.getBufferForFile(ASTFileName, /*IsVolatile=*/false,
-                                         /*RequiresNullTerminator=*/false);
+                                         /*RequiresNullTerminator=*/false,
+                                         /*IsText=*/true);
   if (!Buffer) {
     Diags.Report(diag::err_fe_unable_to_read_pch_file)
         << ASTFileName << Buffer.getError().message();
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
index 4d738e4..7d6239a 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
@@ -353,12 +353,13 @@ DepScanFile::create(EntryRef Entry) {
 }
 
 llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
-DependencyScanningWorkerFilesystem::openFileForRead(const Twine &Path) {
+DependencyScanningWorkerFilesystem::openFileForRead(const Twine &Path,
+                                                    bool IsText) {
   SmallString<256> OwnedFilename;
   StringRef Filename = Path.toStringRef(OwnedFilename);
 
   if (shouldBypass(Filename))
-    return getUnderlyingFS().openFileForRead(Path);
+    return getUnderlyingFS().openFileForRead(Path, IsText);
 
   llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename);
   if (!Result)