[lldb] Turn lldb_private::Status into a value type. (#106163)

This patch removes all of the Set.* methods from Status.

This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.

This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()

Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form

`    ResultTy DoFoo(Status& error)
`
to

`    llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?

The interesting changes are in Status.h and Status.cpp, all other
changes are mostly

` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.

1 files changed, 27 insertions, 21 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
index 345f5cd..f6f13a8 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
@@ -261,8 +261,8 @@ Status GDBRemoteCommunicationServerLLGS::LaunchProcess() {
   Log *log = GetLog(LLDBLog::Process);
 
   if (!m_process_launch_info.GetArguments().GetArgumentCount())
-    return Status("%s: no process command line specified to launch",
-                  __FUNCTION__);
+    return Status::FromErrorStringWithFormat(
+        "%s: no process command line specified to launch", __FUNCTION__);
 
   const bool should_forward_stdio =
       m_process_launch_info.GetFileActionForFD(STDIN_FILENO) == nullptr ||
@@ -348,10 +348,10 @@ Status GDBRemoteCommunicationServerLLGS::AttachToProcess(lldb::pid_t pid) {
   // Before we try to attach, make sure we aren't already monitoring something
   // else.
   if (!m_debugged_processes.empty())
-    return Status("cannot attach to process %" PRIu64
-                  " when another process with pid %" PRIu64
-                  " is being debugged.",
-                  pid, m_current_process->GetID());
+    return Status::FromErrorStringWithFormat(
+        "cannot attach to process %" PRIu64
+        " when another process with pid %" PRIu64 " is being debugged.",
+        pid, m_current_process->GetID());
 
   // Try to attach.
   auto process_or = m_process_manager.Attach(pid, *this);
@@ -447,7 +447,7 @@ Status GDBRemoteCommunicationServerLLGS::AttachWaitProcess(
         error_stream.Format("{0}.", loop_process_list.back().GetProcessID());
 
         Status error;
-        error.SetErrorString(error_stream.GetString());
+        error = Status(error_stream.GetString().str());
         return error;
       }
     }
@@ -1212,14 +1212,15 @@ Status GDBRemoteCommunicationServerLLGS::SetSTDIOFileDescriptor(int fd) {
   std::unique_ptr<ConnectionFileDescriptor> conn_up(
       new ConnectionFileDescriptor(fd, true));
   if (!conn_up) {
-    error.SetErrorString("failed to create ConnectionFileDescriptor");
+    error =
+        Status::FromErrorString("failed to create ConnectionFileDescriptor");
     return error;
   }
 
   m_stdio_communication.SetCloseOnEOF(false);
   m_stdio_communication.SetConnection(std::move(conn_up));
   if (!m_stdio_communication.IsConnected()) {
-    error.SetErrorString(
+    error = Status::FromErrorString(
         "failed to set connection for inferior I/O communication");
     return error;
   }
@@ -1288,7 +1289,7 @@ GDBRemoteCommunicationServerLLGS::Handle_jLLDBTraceSupported(
   // Fail if we don't have a current process.
   if (!m_current_process ||
       (m_current_process->GetID() == LLDB_INVALID_PROCESS_ID))
-    return SendErrorResponse(Status("Process not running."));
+    return SendErrorResponse(Status::FromErrorString("Process not running."));
 
   return SendJSONResponse(m_current_process->TraceSupported());
 }
@@ -1299,7 +1300,7 @@ GDBRemoteCommunicationServerLLGS::Handle_jLLDBTraceStop(
   // Fail if we don't have a current process.
   if (!m_current_process ||
       (m_current_process->GetID() == LLDB_INVALID_PROCESS_ID))
-    return SendErrorResponse(Status("Process not running."));
+    return SendErrorResponse(Status::FromErrorString("Process not running."));
 
   packet.ConsumeFront("jLLDBTraceStop:");
   Expected<TraceStopRequest> stop_request =
@@ -1320,7 +1321,7 @@ GDBRemoteCommunicationServerLLGS::Handle_jLLDBTraceStart(
   // Fail if we don't have a current process.
   if (!m_current_process ||
       (m_current_process->GetID() == LLDB_INVALID_PROCESS_ID))
-    return SendErrorResponse(Status("Process not running."));
+    return SendErrorResponse(Status::FromErrorString("Process not running."));
 
   packet.ConsumeFront("jLLDBTraceStart:");
   Expected<TraceStartRequest> request =
@@ -1341,7 +1342,7 @@ GDBRemoteCommunicationServerLLGS::Handle_jLLDBTraceGetState(
   // Fail if we don't have a current process.
   if (!m_current_process ||
       (m_current_process->GetID() == LLDB_INVALID_PROCESS_ID))
-    return SendErrorResponse(Status("Process not running."));
+    return SendErrorResponse(Status::FromErrorString("Process not running."));
 
   packet.ConsumeFront("jLLDBTraceGetState:");
   Expected<TraceGetStateRequest> request =
@@ -1359,7 +1360,7 @@ GDBRemoteCommunicationServerLLGS::Handle_jLLDBTraceGetBinaryData(
   // Fail if we don't have a current process.
   if (!m_current_process ||
       (m_current_process->GetID() == LLDB_INVALID_PROCESS_ID))
-    return SendErrorResponse(Status("Process not running."));
+    return SendErrorResponse(Status::FromErrorString("Process not running."));
 
   packet.ConsumeFront("jLLDBTraceGetBinaryData:");
   llvm::Expected<TraceGetBinaryDataRequest> request =
@@ -3539,7 +3540,7 @@ GDBRemoteCommunicationServerLLGS::Handle_vRun(
   }
 
   if (argv.empty())
-    return SendErrorResponse(Status("No arguments"));
+    return SendErrorResponse(Status::FromErrorString("No arguments"));
   m_process_launch_info.GetExecutableFile().SetFile(
       m_process_launch_info.GetArguments()[0].ref(), FileSpec::Style::native);
   m_process_launch_error = LaunchProcess();
@@ -3599,7 +3600,8 @@ GDBRemoteCommunicationServerLLGS::Handle_D(StringExtractorGDBRemote &packet) {
   if (detach_error)
     return SendErrorResponse(std::move(detach_error));
   if (!detached)
-    return SendErrorResponse(Status("PID %" PRIu64 " not traced", pid));
+    return SendErrorResponse(
+        Status::FromErrorStringWithFormat("PID %" PRIu64 " not traced", pid));
   return SendOKResponse();
 }
 
@@ -3920,7 +3922,7 @@ GDBRemoteCommunicationServerLLGS::Handle_qSaveCore(
   // Fail if we don't have a current process.
   if (!m_current_process ||
       (m_current_process->GetID() == LLDB_INVALID_PROCESS_ID))
-    return SendErrorResponse(Status("Process not running."));
+    return SendErrorResponse(Status::FromErrorString("Process not running."));
 
   std::string path_hint;
 
@@ -3931,7 +3933,8 @@ GDBRemoteCommunicationServerLLGS::Handle_qSaveCore(
       if (x.consume_front("path-hint:"))
         StringExtractor(x).GetHexByteString(path_hint);
       else
-        return SendErrorResponse(Status("Unsupported qSaveCore option"));
+        return SendErrorResponse(
+            Status::FromErrorString("Unsupported qSaveCore option"));
     }
   }
 
@@ -3982,7 +3985,8 @@ GDBRemoteCommunicationServerLLGS::Handle_QNonStop(
       StartSTDIOForwarding();
     m_non_stop = true;
   } else
-    return SendErrorResponse(Status("Invalid QNonStop packet"));
+    return SendErrorResponse(
+        Status::FromErrorString("Invalid QNonStop packet"));
   return SendOKResponse();
 }
 
@@ -3995,7 +3999,8 @@ GDBRemoteCommunicationServerLLGS::HandleNotificationAck(
   // the last message in the queue is ACK-ed, in which case the packet sends
   // an OK response.
   if (queue.empty())
-    return SendErrorResponse(Status("No pending notification to ack"));
+    return SendErrorResponse(
+        Status::FromErrorString("No pending notification to ack"));
   queue.pop_front();
   if (!queue.empty())
     return SendPacketNoLock(queue.front());
@@ -4025,7 +4030,8 @@ GDBRemoteCommunication::PacketResult
 GDBRemoteCommunicationServerLLGS::Handle_vCtrlC(
     StringExtractorGDBRemote &packet) {
   if (!m_non_stop)
-    return SendErrorResponse(Status("vCtrl is only valid in non-stop mode"));
+    return SendErrorResponse(
+        Status::FromErrorString("vCtrl is only valid in non-stop mode"));
 
   PacketResult interrupt_res = Handle_interrupt(packet);
   // If interrupting the process failed, pass the result through.