[lldb-dap] Avoid creating temporary instances of std::string (NFC) (#140325)

EmplaceSafeString accepts StringRef for the last parameter, str, and
then internally creates a copy of str via StringRef::str or
llvm::json::fixUTF8, so caller do not need to create their own
temporary instances of std::string.

Author: kazutakahirata

lldb/tools/lldb-dap/EventHelper.cpp

@@ -93,7 +93,7 @@ void SendProcessEvent(DAP &dap, LaunchMethod launch_method) {
   exe_fspec.GetPath(exe_path, sizeof(exe_path));
   llvm::json::Object event(CreateEventObject("process"));
   llvm::json::Object body;
-  EmplaceSafeString(body, "name", std::string(exe_path));
+  EmplaceSafeString(body, "name", exe_path);
   const auto pid = dap.target.GetProcess().GetProcessID();
   body.try_emplace("systemProcessId", (int64_t)pid);
   body.try_emplace("isLocalProcess", true);

lldb/tools/lldb-dap/Handler/EvaluateRequestHandler.cpp

@@ -205,7 +205,7 @@ void EvaluateRequestHandler::operator()(
       lldb::SBError error = value.GetError();
       const char *error_cstr = error.GetCString();
       if (error_cstr && error_cstr[0])
-        EmplaceSafeString(response, "message", std::string(error_cstr));
+        EmplaceSafeString(response, "message", error_cstr);
       else
         EmplaceSafeString(response, "message", "evaluate failed");
     } else {

lldb/tools/lldb-dap/Handler/ExceptionInfoRequestHandler.cpp

@@ -136,7 +136,7 @@ void ExceptionInfoRequestHandler::operator()(
     if (!ObjectContainsKey(body, "description")) {
       char description[1024];
       if (thread.GetStopDescription(description, sizeof(description))) {
-        EmplaceSafeString(body, "description", std::string(description));
+        EmplaceSafeString(body, "description", description);
       }
     }
     body.try_emplace("breakMode", "always");

lldb/tools/lldb-dap/JSONUtils.cpp

@@ -905,7 +905,7 @@ llvm::json::Value CreateThreadStopped(DAP &dap, lldb::SBThread &thread,
   if (!ObjectContainsKey(body, "description")) {
     char description[1024];
     if (thread.GetStopDescription(description, sizeof(description))) {
-      EmplaceSafeString(body, "description", std::string(description));
+      EmplaceSafeString(body, "description", description);
     }
   }
   // "threadCausedFocus" is used in tests to validate breaking behavior.