[VFS] Cleanups to VFS interfaces.

Summary:
- add comments clarifying semantics
- Status::copyWithNewName(Status, Name) --> instance method
- Status::copyWithNewName(fs::file_status, Name) --> constructor (it's not a copy)
- File::getName() -> getRealPath(), reflecting its actual behavior/function
  and stop returning status().getName() in the base class (callers can do this
  fallback if they want to, it complicates the contracts).

This is mostly NFC, but the behavior of File::getName() affects FileManager's
FileEntry::tryGetRealPathName(), which now fails in more cases:
 - non-real file cases
 - real-file cases where the underlying vfs::File was opened in a way that
   doesn't call realpath().
(In these cases we don't know a distinct real name, so in principle it seems OK)

Reviewers: klimek

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D49724

llvm-svn: 337834

1 files changed, 19 insertions, 18 deletions

diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp
index bcfcbdbb901..b269a9fcc00 100644
--- a/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/clang/lib/Basic/VirtualFileSystem.cpp
@@ -73,16 +73,14 @@ Status::Status(StringRef Name, UniqueID UID, sys::TimePoint<> MTime,
     : Name(Name), UID(UID), MTime(MTime), User(User), Group(Group), Size(Size),
       Type(Type), Perms(Perms) {}
 
-Status Status::copyWithNewName(const Status &In, StringRef NewName) {
-  return Status(NewName, In.getUniqueID(), In.getLastModificationTime(),
-                In.getUser(), In.getGroup(), In.getSize(), In.getType(),
-                In.getPermissions());
-}
+Status::Status(const file_status &In, StringRef NewName)
+    : Status(NewName, In.getUniqueID(), In.getLastModificationTime(),
+             In.getUser(), In.getGroup(), In.getSize(), In.type(),
+             In.permissions()) {}
 
-Status Status::copyWithNewName(const file_status &In, StringRef NewName) {
-  return Status(NewName, In.getUniqueID(), In.getLastModificationTime(),
-                In.getUser(), In.getGroup(), In.getSize(), In.type(),
-                In.permissions());
+Status Status::copyWithNewName(StringRef NewName) {
+  return Status(NewName, getUniqueID(), getLastModificationTime(), getUser(),
+                getGroup(), getSize(), getType(), getPermissions());
 }
 
 bool Status::equivalent(const Status &Other) const {
@@ -178,6 +176,7 @@ class RealFile : public File {
   Status S;
   std::string RealName;
 
+  // NewRealPathName is used only if non-empty.
   RealFile(int FD, StringRef NewName, StringRef NewRealPathName)
       : FD(FD), S(NewName, {}, {}, {}, {}, {},
                   llvm::sys::fs::file_type::status_error, {}),
@@ -189,7 +188,7 @@ public:
   ~RealFile() override;
 
   ErrorOr<Status> status() override;
-  ErrorOr<std::string> getName() override;
+  Optional<std::string> getRealPath() override;
   ErrorOr<std::unique_ptr<MemoryBuffer>> getBuffer(const Twine &Name,
                                                    int64_t FileSize,
                                                    bool RequiresNullTerminator,
@@ -207,13 +206,15 @@ ErrorOr<Status> RealFile::status() {
     file_status RealStatus;
     if (std::error_code EC = sys::fs::status(FD, RealStatus))
       return EC;
-    S = Status::copyWithNewName(RealStatus, S.getName());
+    S = Status(RealStatus, S.getName());
   }
   return S;
 }
 
-ErrorOr<std::string> RealFile::getName() {
-  return RealName.empty() ? S.getName().str() : RealName;
+Optional<std::string> RealFile::getRealPath() {
+  if (RealName.empty())
+    return llvm::None;
+  return RealName;
 }
 
 ErrorOr<std::unique_ptr<MemoryBuffer>>
@@ -251,7 +252,7 @@ ErrorOr<Status> RealFileSystem::status(const Twine &Path) {
   sys::fs::file_status RealStatus;
   if (std::error_code EC = sys::fs::status(Path, RealStatus))
     return EC;
-  return Status::copyWithNewName(RealStatus, Path.str());
+  return Status(RealStatus, Path.str());
 }
 
 ErrorOr<std::unique_ptr<File>>
@@ -303,7 +304,7 @@ public:
     if (Iter != llvm::sys::fs::directory_iterator()) {
       llvm::sys::fs::file_status S;
       std::error_code ErrorCode = llvm::sys::fs::status(Iter->path(), S, true);
-      CurrentEntry = Status::copyWithNewName(S, Iter->path());
+      CurrentEntry = Status(S, Iter->path());
       if (!EC)
         EC = ErrorCode;
     }
@@ -317,7 +318,7 @@ public:
     } else {
       llvm::sys::fs::file_status S;
       std::error_code ErrorCode = llvm::sys::fs::status(Iter->path(), S, true);
-      CurrentEntry = Status::copyWithNewName(S, Iter->path());
+      CurrentEntry = Status(S, Iter->path());
       if (!EC)
         EC = ErrorCode;
     }
@@ -1641,7 +1642,7 @@ static Status getRedirectedFileStatus(const Twine &Path, bool UseExternalNames,
                                       Status ExternalStatus) {
   Status S = ExternalStatus;
   if (!UseExternalNames)
-    S = Status::copyWithNewName(S, Path.str());
+    S = S.copyWithNewName(Path.str());
   S.IsVFSMapped = true;
   return S;
 }
@@ -1657,7 +1658,7 @@ ErrorOr<Status> RedirectingFileSystem::status(const Twine &Path, Entry *E) {
     return S;
   } else { // directory
     auto *DE = cast<RedirectingDirectoryEntry>(E);
-    return Status::copyWithNewName(DE->getStatus(), Path.str());
+    return DE->getStatus().copyWithNewName(Path.str());
   }
 }