Use write_escaped_string to std::filesystem::path.

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

include/fmt/std.h

@@ -20,8 +20,35 @@
 #  include <filesystem>
 
 FMT_BEGIN_NAMESPACE
+
+namespace detail {
+
 template <typename Char>
-struct formatter<std::filesystem::path, Char> : basic_ostream_formatter<Char> {
+void write_escaped_path(basic_memory_buffer<Char>& quoted,
+                        const std::filesystem::path& p) {
+  write_escaped_string<Char>(std::back_inserter(quoted), p.string<Char>());
+}
+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_string<std::filesystem::path::value_type>(
+      std::back_inserter(quoted), p.native());
+}
+
+}  // namespace detail
+
+template <typename 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

test/std-test.cc

@@ -12,6 +12,8 @@
 TEST(std_test, path) {
 #ifdef __cpp_lib_filesystem
   EXPECT_EQ(fmt::format("{:8}", std::filesystem::path("foo")), "\"foo\"   ");
+  EXPECT_EQ(fmt::format("{}", std::filesystem::path("foo\"bar.txt")),
+            "\"foo\\\"bar.txt\"");
 #endif
 }