From 0a2de6fb327dfa25a8f0feb48d0a5f824c344e89 Mon Sep 17 00:00:00 2001
From: Roman Koshelev <roman.koshelev@bk.ru>
Date: Sun, 1 Jan 2023 17:21:52 +0300
Subject: [PATCH] Fix errors setting of FMT_USE_FLOAT128

---
 include/fmt/format.h | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index 8f05c7d9..76fb60a3 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -786,12 +786,24 @@ using is_integer =
                   !std::is_same<T, wchar_t>::value>;
 
 #ifndef FMT_USE_FLOAT128
-#  ifdef __SIZEOF_FLOAT128__
-#    define FMT_USE_FLOAT128 1
-#  else
+#  ifdef __clang__
+// Clang C++ emulates GCC, so it has to appear early.
+#    if defined(__has_include)
+#      if __has_include(<quadmath.h>)
+#        define FMT_USE_FLOAT128 1
+#      endif
+#    endif
+#  elif defined(__GNUC__)
+// GNU C++:
+#    if defined(_GLIBCXX_USE_FLOAT128) && !defined(__STRICT_ANSI__)
+#      define FMT_USE_FLOAT128 1
+#    endif
+#  endif
+#  ifndef FMT_USE_FLOAT128
 #    define FMT_USE_FLOAT128 0
 #  endif
 #endif
+
 #if FMT_USE_FLOAT128
 using float128 = __float128;
 #else