"Are You Sure" Modal when saving over already existing file #6

I'm not sure if this is planned or not, but a suggestion I'd have for this project is a modal popup specifically during the "Save" version of the dialog. If the user tries to save over a file that already exists, tested likely through an std::ios::in std::fstream, the file dialog opens a confirmation window asking the user if they want to overwrite that file.

Hypothetically speaking, this could probably be cleanly implemented into the FileDialog::m_finalize function:

/* ERRONEOUS DETAIL REMOVED */
if (m_type == IFD_DIALOG_SAVE) {
	// add the extension
	if (m_filterSelection < m_filterExtensions.size() && m_filterExtensions[m_filterSelection].size() > 0) {
		if (!m_result.back().has_extension()) {
			std::string extAdd = m_filterExtensions[m_filterSelection][0];
			m_result.back().replace_extension(extAdd);
		}
	}

	std::fstream m_checkfile;
	m_checkfile.open(/*filename here*/, std::ios::in);
	if (m_checkfile.is_open())
	{
		m_checkfile.close();
		ImGui::OpenPopup("OnOverwriteFilePopup");
		return false
	}
}
/* ... */

I really think that this would drastically increase usability of the product, as users wouldn't be accidentally overwriting files that already existed.