From d326c7298ac6804dba9264624c9df920c084d6a0 Mon Sep 17 00:00:00 2001
From: Vladislav Shchapov <vladislav@shchapov.ru>
Date: Tue, 30 Jul 2024 19:27:11 +0500
Subject: [PATCH] Fix conversion a surrogate pair (#4095)

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>
---
 include/fmt/format.h | 4 +++-
 test/std-test.cc     | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index 708c9051334e..98896bb7c517 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1418,10 +1418,12 @@ template <typename WChar, typename Buffer = memory_buffer> class to_utf8 {
           if (policy == to_utf8_error_policy::abort) return false;
           buf.append(string_view("\xEF\xBF\xBD"));
           --p;
+          continue;
         } else {
           c = (c << 10) + static_cast<uint32_t>(*p) - 0x35fdc00;
         }
-      } else if (c < 0x80) {
+      }
+      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/test/std-test.cc b/test/std-test.cc
index 1327fe8279fd..bcc7bd5f655d 100644
--- a/test/std-test.cc
+++ b/test/std-test.cc
@@ -35,6 +35,9 @@ TEST(std_test, path) {
                                    L"\x0447\x044B\x043D\x0430")),
             "Шчучыншчына");
   EXPECT_EQ(fmt::format("{}", path(L"\xd800")), "�");
+  EXPECT_EQ(fmt::format("{}", path(L"HEAD \xd800 TAIL")), "HEAD � TAIL");
+  EXPECT_EQ(fmt::format("{}", path(L"HEAD \xD83D\xDE00 TAIL")), "HEAD \xF0\x9F\x98\x80 TAIL");
+  EXPECT_EQ(fmt::format("{}", path(L"HEAD \xD83D\xD83D\xDE00 TAIL")), "HEAD �\xF0\x9F\x98\x80 TAIL");
   EXPECT_EQ(fmt::format("{:?}", path(L"\xd800")), "\"\\ud800\"");
 #  endif
 }