Use custom escaping function to std::filesystem::path.

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>

include/fmt/std.h

@@ -20,8 +20,53 @@
 #  include <filesystem>
 
 FMT_BEGIN_NAMESPACE
+
+namespace detail {
+
+template <typename Char>
+void write_escaped_path_impl(basic_memory_buffer<Char>& quoted,
+                             const basic_string_view<Char>& sv) {
+  quoted.push_back(Char('"'));
+  for (auto i = sv.begin(); i != sv.end(); ++i) {
+    switch (*i) {
+    case Char('"'):
+      FMT_FALLTHROUGH;
+    case Char('\\'):
+      quoted.push_back(Char('\\'));
+      FMT_FALLTHROUGH;
+    default:
+      quoted.push_back(*i);
+    }
+  }
+  quoted.push_back(Char('"'));
+}
+template <typename Char>
+void write_escaped_path(basic_memory_buffer<Char>& quoted,
+                        const std::filesystem::path& p) {
+  auto str = p.string<Char>();
+  write_escaped_path_impl<Char>(quoted, str);
+}
+template <>
+void write_escaped_path<std::filesystem::path::value_type>(
+    basic_memory_buffer<std::filesystem::path::value_type>& quoted,
+    const std::filesystem::path& p) {
+  write_escaped_path_impl<std::filesystem::path::value_type>(quoted,
+                                                             p.native());
+}
+
+}  // namespace detail
+
 template <typename Char>
-struct formatter<std::filesystem::path, Char> : basic_ostream_formatter<Char> {
+struct formatter<std::filesystem::path, Char>
+    : formatter<basic_string_view<Char>> {
+  template <typename FormatContext>
+  auto format(const std::filesystem::path& p, FormatContext& ctx) const ->
+      typename FormatContext::iterator {
+    basic_memory_buffer<Char> quoted;
+    detail::write_escaped_path(quoted, p);
+    return formatter<basic_string_view<Char>>::format(
+        basic_string_view<Char>(quoted.data(), quoted.size()), ctx);
+  }
 };
 FMT_END_NAMESPACE
 #endif