[lldb][NFCI] Minor refactor to CommandObjectProcessHandle::VerifyCommandOptionValue

I was refactoring something else but ran into this function. It was
somewhat confusing to read through and understand, but it boils down to
two steps:
- First we try `OptionArgParser::ToBoolean`. If that works, then we're
  good to go.
- Second, we try `llvm::to_integer` to see if it's an integer. If it
  parses to 0 or 1, we're good.
- Failing either of the steps above means we cannot parse it into a
  bool.

Instead of having an integer out param and a bool return value, it seems
like the interface is better served with an optional<bool> -- Either it
parses into true or false, or you get back nothing (nullopt).

Author: bulbazord

lldb/source/Commands/CommandObjectProcess.cpp

@@ -1591,24 +1591,24 @@ class CommandObjectProcessHandle : public CommandObjectParsed {
 
   Options *GetOptions() override { return &m_options; }
 
-  bool VerifyCommandOptionValue(const std::string &option, int &real_value) {
-    bool okay = true;
+  std::optional<bool> VerifyCommandOptionValue(const std::string &option) {
+    if (option.empty())
+      return std::nullopt;
+
     bool success = false;
     bool tmp_value = OptionArgParser::ToBoolean(option, false, &success);
+    if (success)
+      return tmp_value;
+
+    int parsed_value = -1;
+    if (llvm::to_integer(option, parsed_value)) {
+      if (parsed_value != 0 && parsed_value != 1)
+        return std::nullopt;
 
-    if (success && tmp_value)
-      real_value = 1;
-    else if (success && !tmp_value)
-      real_value = 0;
-    else {
-      // If the value isn't 'true' or 'false', it had better be 0 or 1.
-      if (!llvm::to_integer(option, real_value))
-        real_value = 3;
-      if (real_value != 0 && real_value != 1)
-        okay = false;
+      return parsed_value == 0 ? false : true;
     }
 
-    return okay;
+    return std::nullopt;
   }
 
   void PrintSignalHeader(Stream &str) {
@@ -1666,33 +1666,31 @@ class CommandObjectProcessHandle : public CommandObjectParsed {
     // the user's options.
     ProcessSP process_sp = target.GetProcessSP();
 
-    int stop_action = -1;   // -1 means leave the current setting alone
-    int pass_action = -1;   // -1 means leave the current setting alone
-    int notify_action = -1; // -1 means leave the current setting alone
+    std::optional<bool> stop_action = VerifyCommandOptionValue(m_options.stop);
+    std::optional<bool> pass_action = VerifyCommandOptionValue(m_options.pass);
+    std::optional<bool> notify_action =
+        VerifyCommandOptionValue(m_options.notify);
 
-    if (!m_options.stop.empty() &&
-        !VerifyCommandOptionValue(m_options.stop, stop_action)) {
+    if (!m_options.stop.empty() && !stop_action.has_value()) {
       result.AppendError("Invalid argument for command option --stop; must be "
                          "true or false.\n");
       return;
     }
 
-    if (!m_options.notify.empty() &&
-        !VerifyCommandOptionValue(m_options.notify, notify_action)) {
-      result.AppendError("Invalid argument for command option --notify; must "
-                         "be true or false.\n");
+    if (!m_options.pass.empty() && !pass_action.has_value()) {
+      result.AppendError("Invalid argument for command option --pass; must be "
+                         "true or false.\n");
       return;
     }
 
-    if (!m_options.pass.empty() &&
-        !VerifyCommandOptionValue(m_options.pass, pass_action)) {
-      result.AppendError("Invalid argument for command option --pass; must be "
-                         "true or false.\n");
+    if (!m_options.notify.empty() && !notify_action.has_value()) {
+      result.AppendError("Invalid argument for command option --notify; must "
+                         "be true or false.\n");
       return;
     }
 
-    bool no_actions = (stop_action == -1 && pass_action == -1
-        && notify_action == -1);
+    bool no_actions = (!stop_action.has_value() && !pass_action.has_value() &&
+                       !notify_action.has_value());
     if (m_options.only_target_values && !no_actions) {
       result.AppendError("-t is for reporting, not setting, target values.");
       return;
@@ -1732,14 +1730,14 @@ class CommandObjectProcessHandle : public CommandObjectParsed {
           if (signo != LLDB_INVALID_SIGNAL_NUMBER) {
             // Casting the actions as bools here should be okay, because
             // VerifyCommandOptionValue guarantees the value is either 0 or 1.
-            if (stop_action != -1)
-              signals_sp->SetShouldStop(signo, stop_action);
-            if (pass_action != -1) {
-              bool suppress = !pass_action;
+            if (stop_action.has_value())
+              signals_sp->SetShouldStop(signo, *stop_action);
+            if (pass_action.has_value()) {
+              bool suppress = !*pass_action;
               signals_sp->SetShouldSuppress(signo, suppress);
             }
-            if (notify_action != -1)
-              signals_sp->SetShouldNotify(signo, notify_action);
+            if (notify_action.has_value())
+              signals_sp->SetShouldNotify(signo, *notify_action);
             ++num_signals_set;
           } else {
             result.AppendErrorWithFormat("Invalid signal name '%s'\n",
@@ -1759,40 +1757,35 @@ class CommandObjectProcessHandle : public CommandObjectParsed {
           }
          num_signals_set = num_args;
         }
-        auto set_lazy_bool = [] (int action) -> LazyBool {
-          LazyBool lazy;
-          if (action == -1)
-            lazy = eLazyBoolCalculate;
-          else if (action)
-            lazy = eLazyBoolYes;
-          else
-            lazy = eLazyBoolNo;
-          return lazy;
+        auto set_lazy_bool = [](std::optional<bool> action) -> LazyBool {
+          if (!action.has_value())
+            return eLazyBoolCalculate;
+          return (*action) ? eLazyBoolYes : eLazyBoolNo;
         };
 
         // If there were no actions, we're just listing, don't add the dummy:
         if (!no_actions)
-          target.AddDummySignal(arg.ref(),
-                                set_lazy_bool(pass_action),
-                                set_lazy_bool(notify_action),
-                                set_lazy_bool(stop_action));
+         target.AddDummySignal(arg.ref(), set_lazy_bool(pass_action),
+                               set_lazy_bool(notify_action),
+                               set_lazy_bool(stop_action));
       }
     } else {
       // No signal specified, if any command options were specified, update ALL
       // signals.  But we can't do this without a process since we don't know
       // all the possible signals that might be valid for this target.
-      if (((notify_action != -1) || (stop_action != -1) || (pass_action != -1))
-          && process_sp) {
+      if ((notify_action.has_value() || stop_action.has_value() ||
+           pass_action.has_value()) &&
+          process_sp) {
         if (m_interpreter.Confirm(
                 "Do you really want to update all the signals?", false)) {
           int32_t signo = signals_sp->GetFirstSignalNumber();
           while (signo != LLDB_INVALID_SIGNAL_NUMBER) {
-            if (notify_action != -1)
-              signals_sp->SetShouldNotify(signo, notify_action);
-            if (stop_action != -1)
-              signals_sp->SetShouldStop(signo, stop_action);
-            if (pass_action != -1) {
-              bool suppress = !pass_action;
+            if (notify_action.has_value())
+              signals_sp->SetShouldNotify(signo, *notify_action);
+            if (stop_action.has_value())
+              signals_sp->SetShouldStop(signo, *stop_action);
+            if (pass_action.has_value()) {
+              bool suppress = !*pass_action;
               signals_sp->SetShouldSuppress(signo, suppress);
             }
             signo = signals_sp->GetNextSignalNumber(signo);