From 99070899b7476da670fc7a70c4515ddf3bab2bfc Mon Sep 17 00:00:00 2001
From: Roman-Koshelev <34384083+Roman-Koshelev@users.noreply.github.com>
Date: Wed, 8 Feb 2023 18:15:02 +0300
Subject: [PATCH] Fix errors setting of FMT_USE_FLOAT128 (#3259)

---
 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 4a1663bb..b65360d1 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -798,12 +798,24 @@ 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