use Twine instead of char* for function args (llvm#165569)

Changed the function arguments to take `const Twine&` instead of `const
char*`. This will avoid converting StringRef's to C strings too soon (or
ever).

Author: perry-ca

clang/lib/Basic/SourceManager.cpp

@@ -608,8 +608,7 @@ FileID SourceManager::createFileIDImpl(ContentCache &File, StringRef Filename,
     return FileID::get(LoadedID);
   }
   unsigned FileSize = File.getSize();
-  llvm::ErrorOr<bool> NeedConversion =
-      llvm::needConversion(Filename.str().c_str());
+  llvm::ErrorOr<bool> NeedConversion = llvm::needConversion(Filename);
   if (NeedConversion && *NeedConversion) {
     // Buffer size may increase due to potential z/OS EBCDIC to UTF-8
     // conversion.

llvm/include/llvm/Support/AutoConvert.h

@@ -18,6 +18,7 @@
 #include <_Ccsid.h>
 #endif
 #ifdef __cplusplus
+#include "llvm/ADT/Twine.h"
 #include "llvm/Support/Error.h"
 #include <system_error>
 #endif /* __cplusplus */
@@ -47,12 +48,12 @@ namespace llvm {
 std::error_code setzOSFileTag(int FD, int CCSID, bool Text);
 
 /** \brief Get the the tag ccsid for a file name or a file descriptor. */
-ErrorOr<__ccsid_t> getzOSFileTag(const char *FileName, const int FD = -1);
+ErrorOr<__ccsid_t> getzOSFileTag(const Twine &FileName, const int FD = -1);
 
 /** \brief Query the file tag to determine if it needs conversion to UTF-8
  *  codepage.
  */
-ErrorOr<bool> needzOSConversion(const char *FileName, const int FD = -1);
+ErrorOr<bool> needzOSConversion(const Twine &FileName, const int FD = -1);
 
 #endif /* __MVS__*/
 
@@ -87,7 +88,7 @@ inline std::error_code setFileTag(int FD, int CCSID, bool Text) {
   return std::error_code();
 }
 
-inline ErrorOr<bool> needConversion(const char *FileName, const int FD = -1) {
+inline ErrorOr<bool> needConversion(const Twine &FileName, const int FD = -1) {
 #ifdef __MVS__
   return needzOSConversion(FileName, FD);
 #endif

llvm/lib/Support/AutoConvert.cpp

@@ -96,7 +96,7 @@ std::error_code llvm::setzOSFileTag(int FD, int CCSID, bool Text) {
   return std::error_code();
 }
 
-ErrorOr<__ccsid_t> llvm::getzOSFileTag(const char *FileName, const int FD) {
+ErrorOr<__ccsid_t> llvm::getzOSFileTag(const Twine &FileName, const int FD) {
   // If we have a file descriptor, use it to find out file tagging. Otherwise we
   // need to use stat() with the file path.
   if (FD != -1) {
@@ -110,12 +110,12 @@ ErrorOr<__ccsid_t> llvm::getzOSFileTag(const char *FileName, const int FD) {
     return Query.fccsid;
   }
   struct stat Attr;
-  if (stat(FileName, &Attr) == -1)
+  if (stat(FileName.str().c_str(), &Attr) == -1)
     return std::error_code(errno, std::generic_category());
   return Attr.st_tag.ft_ccsid;
 }
 
-ErrorOr<bool> llvm::needzOSConversion(const char *FileName, const int FD) {
+ErrorOr<bool> llvm::needzOSConversion(const Twine &FileName, const int FD) {
   ErrorOr<__ccsid_t> Ccsid = getzOSFileTag(FileName, FD);
   if (std::error_code EC = Ccsid.getError())
     return EC;

llvm/lib/Support/MemoryBuffer.cpp

@@ -512,7 +512,7 @@ getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
   }
 
 #ifdef __MVS__
-  ErrorOr<bool> NeedsConversion = needConversion(Filename.str().c_str(), FD);
+  ErrorOr<bool> NeedsConversion = needConversion(Filename, FD);
   if (std::error_code EC = NeedsConversion.getError())
     return EC;
   // File size may increase due to EBCDIC -> UTF-8 conversion, therefore we