[committed 2/2] libstdc++: Use GCC's predefined macro for endianness [PR104080]

[Jonathan Wakely via Gcc-patches]

Tested x86_64-linux, pushed to trunk.


Instead of hardcoded preprocessor conditionals with explicit target
checks, just rely on the fact that __BYTE_ORDER__ is always defined by
GCC.

libstdc++-v3/ChangeLog:

        PR libstdc++/104080
        * src/c++17/fast_float/LOCAL_PATCHES: Update.
        * src/c++17/fast_float/fast_float.h (FASTFLOAT_IS_BIG_ENDIAN):
        Define in terms of __BYTE_ORDER__.
---
 libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES | 1 +
 libstdc++-v3/src/c++17/fast_float/fast_float.h  | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES 
b/libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES
index 447c7ed2cdb..5bb42933398 100644
--- a/libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES
+++ b/libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES
@@ -1,3 +1,4 @@
 r12-6647
 r12-6648
 r12-6664
+r12-6665
diff --git a/libstdc++-v3/src/c++17/fast_float/fast_float.h 
b/libstdc++-v3/src/c++17/fast_float/fast_float.h
index ee129309ba3..31fb88b8aba 100644
--- a/libstdc++-v3/src/c++17/fast_float/fast_float.h
+++ b/libstdc++-v3/src/c++17/fast_float/fast_float.h
@@ -128,7 +128,9 @@ from_chars_result from_chars_advanced(const char *first, 
const char *last,
 #define FASTFLOAT_VISUAL_STUDIO 1
 #endif
 
-#ifdef _WIN32
+#ifdef __BYTE_ORDER__
+#define FASTFLOAT_IS_BIG_ENDIAN (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
+#elif defined _WIN32
 #define FASTFLOAT_IS_BIG_ENDIAN 0
 #else
 #if defined(__APPLE__) || defined(__FreeBSD__)
-- 
2.31.1