Move to llvm::expected, clean up comments

Author: Jlalond

lldb/include/lldb/API/SBSaveCoreOptions.h

@@ -119,8 +119,8 @@ class LLDB_API SBSaveCoreOptions {
   ///   an empty collection will be returned.
   SBThreadCollection GetThreadsToSave() const;
 
-  /// Get the current total number of bytes the core is expected to be but not
-  /// including the overhead of the core file format. Requires a Process and
+  /// Get the current total number of bytes the core is expected to have
+  /// excluding the overhead of the core file format. Requires a Process and
   /// Style to be specified.
   ///
   /// \note

lldb/include/lldb/Symbol/SaveCoreOptions.h

@@ -49,7 +49,7 @@ class SaveCoreOptions {
 
   lldb_private::ThreadCollection::collection GetThreadsToSave() const;
 
-  uint64_t GetCurrentSizeInBytes(Status &error);
+  llvm::Expected<uint64_t> GetCurrentSizeInBytes();
 
   void Clear();
 

lldb/source/API/SBSaveCoreOptions.cpp

@@ -116,7 +116,14 @@ void SBSaveCoreOptions::Clear() {
 
 uint64_t SBSaveCoreOptions::GetCurrentSizeInBytes(SBError &error) {
   LLDB_INSTRUMENT_VA(this, error);
-  return m_opaque_up->GetCurrentSizeInBytes(error.ref());
+  llvm::Expected<uint64_t> expected_bytes = m_opaque_up->GetCurrentSizeInBytes();
+  if (!expected_bytes) {
+    error = SBError(lldb_private::Status::FromError(expected_bytes.takeError()));
+    return 0;
+  }
+  // Clear the error, so if the clearer uses it we set it to success.
+  error.Clear();
+  return *expected_bytes; 
 }
 
 lldb_private::SaveCoreOptions &SBSaveCoreOptions::ref() const {

lldb/source/Symbol/SaveCoreOptions.cpp

@@ -145,20 +145,20 @@ SaveCoreOptions::GetThreadsToSave() const {
   return thread_collection;
 }
 
-uint64_t SaveCoreOptions::GetCurrentSizeInBytes(Status &error) {
-  if (!m_process_sp) {
-    error = Status::FromErrorString("Requires a process to be set.");
-    return 0;
-  }
+llvm::Expected<uint64_t> SaveCoreOptions::GetCurrentSizeInBytes() {
+  Status error;
+  if (!m_process_sp)
+    return Status::FromErrorString("Requires a process to be set.").takeError();
+
 
   error = EnsureValidConfiguration(m_process_sp);
   if (error.Fail())
-    return 0;
+    return error.takeError();
 
   CoreFileMemoryRanges ranges;
   error = m_process_sp->CalculateCoreFileSaveRanges(*this, ranges);
   if (error.Fail())
-    return 0;
+    return error.takeError();
 
   uint64_t total_in_bytes = 0;
   for (auto &core_range : ranges)