Environment

Windows build number: [run "ver" at a command prompt]
Windows Terminal version (if applicable):

Any other software?

Today I modified the Windows Terminal configuration file and wanted to create a Pwsh with the emoji title. However, I encountered some confusion in this process. I checked the task manager and found that conhost did not escape when the process was started, causing the command line to parse the exception.

Steps to reproduce

Expected behavior

I need to start pwsh by the following command line (note that the following command line is in cmd, or you can start pwsh normally using CreateProcessW.)

"C:\Program Files\PowerShell\7-preview\pwsh.exe" -NoExit -Command "$Host.UI.RawUI.WindowTitle=\"Windows Pwsh 💙 (7 Preview)\""

Here is the Windows Terminal configuration file (the command line has been properly escaped):

        {
            "startingDirectory": "C:\\Users\\CharlieInc",
            "guid": "{08a0be98-ff68-4e3a-a054-0fbd3969d3bb}",
            "name": "Windows Pwsh 💙 (7 Preview)",
            "colorscheme": "Campbell",
            "historySize": 9001,
            "snapOnInput": true,
            "cursorColor": "#FFFFFF",
            "cursorShape": "bar",
            "commandline": "\"C:\\Program Files\\PowerShell\\7-preview\\pwsh.exe\" -NoExit -Command \"$Host.UI.RawUI.WindowTitle=\\\"Windows Pwsh 💙 (7 Preview)\\\"\"",
            "fontFace": "Consolas",
            "fontSize": 12,
            "acrylicOpacity": 0.75,
            "useAcrylic": true,
            "closeOnExit": false,
            "padding": "0, 0, 0, 0",
            "icon": "ms-appdata:///roaming/pwsh-32.png"
        }

Actual behavior

As expected, Pwsh should set the title correctly, but pwsh reported the error:

Let's take a look at the command line:

When you see the red line, the command line that pwsh starts is incorrect, and when you start conhost, the command line is still correct!

Currently I have found a suspicious code, most likely this code caused an error:

In this code, command line composition is simply a simple connection rather than a concatenated string. If the string contains spaces, this will result in an incorrect command line.

Below is a code for the command line escaping, which may be useful：

inline std::wstring escape_argument(std::wstring_view ac) {
  if (ac.empty()) {
    return L"\"\"";
  }
  bool hasspace = false;
  auto n = ac.size();
  for (auto c : ac) {
    switch (c) {
    case L'"':
    case L'\\':
      n++;
      break;
    case ' ':
    case '\t':
      hasspace = true;
      break;
    default:
      break;
    }
  }
  if (hasspace) {
    n += 2;
  }
  if (n == ac.size()) {
    return std::wstring(ac.data(), ac.size());
  }
  std::wstring buf;
  if (hasspace) {
    buf.push_back(L'"');
  }
  size_t slashes = 0;
  for (auto c : ac) {
    switch (c) {
    case L'\\':
      slashes++;
      buf.push_back(L'\\');
      break;
    case L'"': {
      for (; slashes > 0; slashes--) {
        buf.push_back(L'\\');
      }
      buf.push_back(L'\\');
      buf.push_back(c);
    } break;
    default:
      slashes = 0;
      buf.push_back(c);
      break;
    }
  }
  if (hasspace) {
    for (; slashes > 0; slashes--) {
      buf.push_back(L'\\');
    }
    buf.push_back(L'"');
  }
  return buf;
}