[lldb] Don't print script output twice in HandleCommand

When executing a script command in HandleCommand(s) we currently print
its output twice
You can see this issue in action when adding a breakpoint command:

(lldb) b main
Breakpoint 1: where = main.out`main + 13 at main.cpp:2:3, address = 0x0000000100003fad
(lldb) break command add 1 -o "script print(\"Hey!\")"
(lldb) r
Process 76041 launched: '/tmp/main.out' (x86_64)
Hey!
(lldb)  script print("Hey!")
Hey!
Process 76041 stopped

The issue is caused by HandleCommands using a temporary
CommandReturnObject and one of the commands (`script` in this case)
setting an immediate output stream. This causes the result to be printed
twice: once directly to the immediate output stream and once when
printing the result of HandleCommands.

This patch fixes the issue by introducing a new option to suppress
immediate output for temporary CommandReturnObjects.

Differential revision: https://reviews.llvm.org/D103349

lldb/include/lldb/Interpreter/CommandReturnObject.h

@@ -63,20 +63,28 @@ public:
   }
 
   void SetImmediateOutputFile(lldb::FileSP file_sp) {
+    if (m_suppress_immediate_output)
+      return;
     lldb::StreamSP stream_sp(new StreamFile(file_sp));
     m_out_stream.SetStreamAtIndex(eImmediateStreamIndex, stream_sp);
   }
 
   void SetImmediateErrorFile(lldb::FileSP file_sp) {
+    if (m_suppress_immediate_output)
+      return;
     lldb::StreamSP stream_sp(new StreamFile(file_sp));
     m_err_stream.SetStreamAtIndex(eImmediateStreamIndex, stream_sp);
   }
 
   void SetImmediateOutputStream(const lldb::StreamSP &stream_sp) {
+    if (m_suppress_immediate_output)
+      return;
     m_out_stream.SetStreamAtIndex(eImmediateStreamIndex, stream_sp);
   }
 
   void SetImmediateErrorStream(const lldb::StreamSP &stream_sp) {
+    if (m_suppress_immediate_output)
+      return;
     m_err_stream.SetStreamAtIndex(eImmediateStreamIndex, stream_sp);
   }
 
@@ -142,16 +150,23 @@ public:
 
   void SetInteractive(bool b);
 
+  bool GetSuppressImmediateOutput() const;
+
+  void SetSuppressImmediateOutput(bool b);
+
 private:
   enum { eStreamStringIndex = 0, eImmediateStreamIndex = 1 };
 
   StreamTee m_out_stream;
   StreamTee m_err_stream;
 
-  lldb::ReturnStatus m_status;
-  bool m_did_change_process_state;
-  bool m_interactive; // If true, then the input handle from the debugger will
-                      // be hooked up
+  lldb::ReturnStatus m_status = lldb::eReturnStatusStarted;
+
+  bool m_did_change_process_state = false;
+  bool m_suppress_immediate_output = false;
+
+  /// If true, then the input handle from the debugger will be hooked up.
+  bool m_interactive = true;
 };
 
 } // namespace lldb_private

lldb/lldb/test/Shell/Breakpoint/breakpoint-command.test

@@ -0,0 +1,5 @@
+# RUN: %build %p/Inputs/dummy-target.c -o %t.out
+# RUN: %lldb %t.out -o 'b main' -o 'break command add 1 -o "script print(95000 + 126)"' -o 'r'
+
+# CHECK: 95125
+# CHECK-NOT: 95126

lldb/source/Interpreter/CommandInterpreter.cpp

@@ -2306,6 +2306,7 @@ void CommandInterpreter::HandleCommands(const StringList &commands,
 
     CommandReturnObject tmp_result(m_debugger.GetUseColor());
     tmp_result.SetInteractive(result.GetInteractive());
+    tmp_result.SetSuppressImmediateOutput(true);
 
     // We might call into a regex or alias command, in which case the
     // add_to_history will get lost.  This m_command_source_depth dingus is the

lldb/source/Interpreter/CommandReturnObject.cpp

@@ -41,9 +41,7 @@ static void DumpStringToStreamWithNewline(Stream &strm, const std::string &s) {
 }
 
 CommandReturnObject::CommandReturnObject(bool colors)
-    : m_out_stream(colors), m_err_stream(colors),
-      m_status(eReturnStatusStarted), m_did_change_process_state(false),
-      m_interactive(true) {}
+    : m_out_stream(colors), m_err_stream(colors) {}
 
 void CommandReturnObject::AppendErrorWithFormat(const char *format, ...) {
   SetStatus(eReturnStatusFailed);
@@ -154,6 +152,7 @@ void CommandReturnObject::Clear() {
     static_cast<StreamString *>(stream_sp.get())->Clear();
   m_status = eReturnStatusStarted;
   m_did_change_process_state = false;
+  m_suppress_immediate_output = false;
   m_interactive = true;
 }
 
@@ -168,3 +167,11 @@ void CommandReturnObject::SetDidChangeProcessState(bool b) {
 bool CommandReturnObject::GetInteractive() const { return m_interactive; }
 
 void CommandReturnObject::SetInteractive(bool b) { m_interactive = b; }
+
+bool CommandReturnObject::GetSuppressImmediateOutput() const {
+  return m_suppress_immediate_output;
+}
+
+void CommandReturnObject::SetSuppressImmediateOutput(bool b) {
+  m_suppress_immediate_output = b;
+}

lldb/test/Shell/Breakpoint/breakpoint-command.test

@@ -0,0 +1,5 @@
+# RUN: %build %p/Inputs/dummy-target.c -o %t.out
+# RUN: %lldb %t.out -o 'b main' -o 'break command add 1 -o "script print(95000 + 126)"' -o 'r'
+
+# CHECK: 95125
+# CHECK-NOT: 95126

lldb/test/Shell/ScriptInterpreter/Lua/nested_sessions.test

@@ -7,6 +7,5 @@
 # CHECK-NEXT: foo foo
 # CHECK-NEXT: foo bar
 # CHECK-NEXT: foo bar
-# CHECK-NEXT: foo bar
 # CHECK: script
 # CHECK-NEXT: bar bar