From 6a2495c84009903cc7bc3414757164a5e1d6069f Mon Sep 17 00:00:00 2001
From: Alexey Ochapov <alexez@alexez.com>
Date: Thu, 5 Nov 2020 04:11:31 +0300
Subject: [PATCH] -Wattributes visibility warning with some GCC versions
 (#1975)

---
 include/fmt/format.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index ea45429f..537bd9c4 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -69,6 +69,13 @@
 #  define FMT_NOINLINE
 #endif
 
+// Special definition specific to GCC only
+#if FMT_GCC_VERSION
+#  define FMT_GCC_VISIBILITY_HIDDEN __attribute__((visibility("hidden")))
+#else
+#  define FMT_GCC_VISIBILITY_HIDDEN
+#endif
+
 #if __cplusplus == 201103L || __cplusplus == 201402L
 #  if defined(__INTEL_COMPILER) || defined(__PGI)
 #    define FMT_FALLTHROUGH
@@ -3200,8 +3207,10 @@ FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
 
 #define FMT_STRING_IMPL(s, base)                                  \
   [] {                                                            \
+    /* Use a hidden visibility as workaround for some GCC, see */ \
+    /* https://github.com/fmtlib/fmt/issues/1973 for details */   \
     /* Use a macro-like name to avoid shadowing warnings. */      \
-    struct FMT_COMPILE_STRING : base {                            \
+    struct FMT_GCC_VISIBILITY_HIDDEN FMT_COMPILE_STRING : base {  \
       using char_type = fmt::remove_cvref_t<decltype(s[0])>;      \
       FMT_MAYBE_UNUSED FMT_CONSTEXPR                              \
       operator fmt::basic_string_view<char_type>() const {        \