From 3dec65b7fd8df55bd5904a1e22dd907038634cf0 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@meta.com>
Date: Sat, 22 Jul 2023 06:56:52 -0700
Subject: [PATCH] Use replacement character in path

---
 include/fmt/format.h | 15 ++++++++-------
 include/fmt/std.h    |  2 +-
 test/std-test.cc     | 21 +++++++++++----------
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index 690dfb00dd1c..7181780f0aea 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1421,11 +1421,11 @@ template <typename WChar, typename Buffer = memory_buffer> class to_utf8 {
 
  public:
   to_utf8() {}
-  explicit to_utf8(basic_string_view<WChar> s) {
+  explicit to_utf8(basic_string_view<WChar> s,
+                   to_utf8_error_policy policy = to_utf8_error_policy::abort) {
     static_assert(sizeof(WChar) == 2 || sizeof(WChar) == 4,
                   "Expect utf16 or utf32");
-
-    if (!convert(s))
+    if (!convert(s, policy))
       FMT_THROW(std::runtime_error(sizeof(WChar) == 2 ? "invalid utf16"
                                                       : "invalid utf32"));
   }
@@ -1437,8 +1437,9 @@ template <typename WChar, typename Buffer = memory_buffer> class to_utf8 {
   // Performs conversion returning a bool instead of throwing exception on
   // conversion error. This method may still throw in case of memory allocation
   // error.
-  bool convert(basic_string_view<WChar> s) {
-    if (!convert(buffer_, s)) return false;
+  bool convert(basic_string_view<WChar> s,
+               to_utf8_error_policy policy = to_utf8_error_policy::abort) {
+    if (!convert(buffer_, s, policy)) return false;
     buffer_.push_back(0);
     return true;
   }
@@ -1453,11 +1454,11 @@ template <typename WChar, typename Buffer = memory_buffer> class to_utf8 {
         if (p == s.end() || (c & 0xfc00) != 0xd800 || (*p & 0xfc00) != 0xdc00) {
           if (policy == to_utf8_error_policy::abort) return false;
           buf.append(string_view("�"));
+          --p;
         } else {
           c = (c << 10) + static_cast<uint32_t>(*p) - 0x35fdc00;
         }
-      }
-      if (c < 0x80) {
+      } else if (c < 0x80) {
         buf.push_back(static_cast<char>(c));
       } else if (c < 0x800) {
         buf.push_back(static_cast<char>(0xc0 | (c >> 6)));
diff --git a/include/fmt/std.h b/include/fmt/std.h
index 7ac81aeab8e8..8135f757eafe 100644
--- a/include/fmt/std.h
+++ b/include/fmt/std.h
@@ -74,7 +74,7 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,
 #  ifdef _WIN32
 template <>
 auto get_path_string<char>(const std::filesystem::path& p) {
-  return to_utf8<wchar_t>(p.native());
+  return to_utf8<wchar_t>(p.native(), to_utf8_error_policy::replace);
 }
 
 template <>
diff --git a/test/std-test.cc b/test/std-test.cc
index 35867f05a891..fda8e96bd122 100644
--- a/test/std-test.cc
+++ b/test/std-test.cc
@@ -15,23 +15,23 @@
 #include "fmt/ranges.h"
 #include "gtest-extra.h"  // StartsWith
 
-using testing::StartsWith;
-
 #ifdef __cpp_lib_filesystem
 TEST(std_test, path) {
-  EXPECT_EQ(fmt::format("{:8}", std::filesystem::path("foo")), "foo     ");
-  EXPECT_EQ(fmt::format("{}", std::filesystem::path("foo\"bar.txt")),
-            "foo\"bar.txt");
-  EXPECT_EQ(fmt::format("{:?}", std::filesystem::path("foo\"bar.txt")),
-            "\"foo\\\"bar.txt\"");
+  using std::filesystem::path;
+  EXPECT_EQ(fmt::format("{}", path("/usr/bin")), "/usr/bin");
+  EXPECT_EQ(fmt::format("{:?}", path("/usr/bin")), "\"/usr/bin\"");
+  EXPECT_EQ(fmt::format("{:8}", path("foo")), "foo     ");
+
+  EXPECT_EQ(fmt::format("{}", path("foo\"bar")), "foo\"bar");
+  EXPECT_EQ(fmt::format("{:?}", path("foo\"bar")), "\"foo\\\"bar\"");
 
 #  ifdef _WIN32
-  EXPECT_EQ(fmt::format("{}", std::filesystem::path(
+  EXPECT_EQ(fmt::format("{}", path(
                                   L"\x0428\x0447\x0443\x0447\x044B\x043D\x0448"
                                   L"\x0447\x044B\x043D\x0430")),
             "Шчучыншчына");
-  EXPECT_EQ(fmt::format("{:?}", std::filesystem::path(L"\xd800")),
-            "\"\\ud800\"");
+  EXPECT_EQ(fmt::format("{}", path(L"\xd800")), "�");
+  EXPECT_EQ(fmt::format("{:?}", path(L"\xd800")), "\"\\ud800\"");
 #  endif
 }
 
@@ -191,6 +191,7 @@ const char* my_exception::what() const noexcept { return msg.c_str(); }
 }  // namespace my_ns1
 
 TEST(std_test, exception) {
+  using testing::StartsWith;
   exception_test<std::exception>();
   exception_test<std::runtime_error>();