From adb4f149c0655c3d12e033cff11f5830b5234bf9 Mon Sep 17 00:00:00 2001
From: NgoQuocViet2001 <ngoquocviet2001@gmail.com>
Date: Sat, 24 Oct 2026 22:39:30 +0700
Subject: [PATCH 1/2] Fix generic path format when formatting to wide strings

get_path_string used the native or generic string computed by the path
formatter only when converting wchar_t to UTF-8 and fell back to
p.string<Char>() otherwise, so the 'g' specifier was ignored when the
output character type matched path::value_type. On Windows,
fmt::format(L"{:g}", path(L"C:\\foo")) returned L"C:\\foo" instead of
L"C:/foo". Use the passed string in that case, as write_escaped_path
already does.
---
 include/fmt/std.h | 2 ++
 test/std-test.cc  | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/include/fmt/std.h b/include/fmt/std.h
index 2bab00f2..a8f7c9f1 100644
--- a/include/fmt/std.h
+++ b/include/fmt/std.h
@@ -107,6 +107,8 @@ auto get_path_string(const std::filesystem::path& p,
   if constexpr (std::is_same_v<Char, char> &&
                 std::is_same_v<PathChar, wchar_t>) {
     return to_utf8<wchar_t>(native, to_utf8_error_policy::wtf);
+  } else if constexpr (std::is_same_v<Char, PathChar>) {
+    return native;
   } else {
     return p.string<Char>();
   }
diff --git a/test/std-test.cc b/test/std-test.cc
index eaf238b4..32f77e55 100644
--- a/test/std-test.cc
+++ b/test/std-test.cc
@@ -14,6 +14,7 @@
 
 #include "fmt/os.h"  // fmt::system_category
 #include "fmt/ranges.h"
+#include "fmt/xchar.h"
 #include "gtest-extra.h"  // StartsWith
 
 #ifdef __cpp_lib_filesystem
@@ -35,6 +36,8 @@ TEST(std_test, path) {
 #  ifdef _WIN32
   EXPECT_EQ(fmt::format("{}", path("C:\\foo")), "C:\\foo");
   EXPECT_EQ(fmt::format("{:g}", path("C:\\foo")), "C:/foo");
+  EXPECT_EQ(fmt::format(L"{}", path(L"C:\\foo")), L"C:\\foo");
+  EXPECT_EQ(fmt::format(L"{:g}", path(L"C:\\foo")), L"C:/foo");
 
   EXPECT_EQ(fmt::format("{}", path(L"\x0428\x0447\x0443\x0447\x044B\x043D\x0448"
                                    L"\x0447\x044B\x043D\x0430")),

From 0fe44d56d006d4750b41f4ebe056b9fe69902599 Mon Sep 17 00:00:00 2001
From: NgoQuocViet2001 <ngoquocviet2001@gmail.com>
Date: Wed, 28 Oct 2026 15:12:54 +0700
Subject: [PATCH 2/2] Keep generic path format when converting to wide strings
 on POSIX

---
 include/fmt/std.h | 13 ++++++-------
 test/std-test.cc  |  7 +++++++
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/fmt/std.h b/include/fmt/std.h
index a8f7c9f1..6ff7de63 100644
--- a/include/fmt/std.h
+++ b/include/fmt/std.h
@@ -102,21 +102,19 @@ template <int N> struct ubitint {};
 #if FMT_CPP_LIB_FILESYSTEM
 
 template <typename Char, typename PathChar>
-auto get_path_string(const std::filesystem::path& p,
-                     const std::basic_string<PathChar>& native) {
+auto get_path_string(const std::basic_string<PathChar>& native) {
   if constexpr (std::is_same_v<Char, char> &&
                 std::is_same_v<PathChar, wchar_t>) {
     return to_utf8<wchar_t>(native, to_utf8_error_policy::wtf);
   } else if constexpr (std::is_same_v<Char, PathChar>) {
     return native;
   } else {
-    return p.string<Char>();
+    return std::filesystem::path(native).string<Char>();
   }
 }
 
 template <typename Char, typename PathChar>
 void write_escaped_path(basic_memory_buffer<Char>& quoted,
-                        const std::filesystem::path& p,
                         const std::basic_string<PathChar>& native) {
   if constexpr (std::is_same_v<Char, char> &&
                 std::is_same_v<PathChar, wchar_t>) {
@@ -128,7 +126,8 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,
     write_escaped_string<std::filesystem::path::value_type>(
         std::back_inserter(quoted), native);
   } else {
-    write_escaped_string<Char>(std::back_inserter(quoted), p.string<Char>());
+    write_escaped_string<Char>(std::back_inserter(quoted),
+                               std::filesystem::path(native).string<Char>());
   }
 }
 
@@ -339,11 +338,11 @@ template <typename Char> struct formatter<std::filesystem::path, Char> {
     detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
                                 ctx);
     if (!debug_) {
-      auto s = detail::get_path_string<Char>(p, path_string);
+      auto s = detail::get_path_string<Char>(path_string);
       return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
     }
     auto quoted = basic_memory_buffer<Char>();
-    detail::write_escaped_path(quoted, p, path_string);
+    detail::write_escaped_path(quoted, path_string);
     return detail::write(ctx.out(),
                          basic_string_view<Char>(quoted.data(), quoted.size()),
                          specs);
diff --git a/test/std-test.cc b/test/std-test.cc
index 32f77e55..7d992584 100644
--- a/test/std-test.cc
+++ b/test/std-test.cc
@@ -33,6 +33,13 @@ TEST(std_test, path) {
   EXPECT_EQ(fmt::format("{:?}", path("foo\"bar")), "\"foo\\\"bar\"");
 
   EXPECT_EQ(fmt::format("{:g}", path("/usr/bin")), "/usr/bin");
+
+  // libstdc++ collapses repeated separators in the generic format.
+  const path repeated = "a//b";
+  EXPECT_EQ(fmt::format("{:g}", repeated), repeated.generic_string());
+  EXPECT_EQ(fmt::format(L"{:g}", repeated), repeated.generic_wstring());
+  EXPECT_EQ(fmt::format(L"{:?g}", repeated),
+            L"\"" + repeated.generic_wstring() + L"\"");
 #  ifdef _WIN32
   EXPECT_EQ(fmt::format("{}", path("C:\\foo")), "C:\\foo");
   EXPECT_EQ(fmt::format("{:g}", path("C:\\foo")), "C:/foo");