From f74736dd143843da3dc15103ffcdaa6d8d20cc39 Mon Sep 17 00:00:00 2001
From: Alexey Ochapov <alexez@alexez.com>
Date: Wed, 4 Nov 2020 23:47:25 +0300
Subject: [PATCH] FMT_COMPILE_STRING_VISIBILITY_ATTRIBUTE ->
 FMT_GCC_VISIBILITY_HIDDEN, add comments

---
 include/fmt/format.h | 38 ++++++++++++++++++++------------------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index 7de07422..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
@@ -3198,24 +3205,19 @@ FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
   return {s.data(), s.size()};
 }
 
-#if FMT_GCC_VERSION
-#  define FMT_COMPILE_STRING_VISIBILITY_ATTRIBUTE \
-    __attribute__((visibility("hidden")))
-#else
-#  define FMT_COMPILE_STRING_VISIBILITY_ATTRIBUTE
-#endif
-
-#define FMT_STRING_IMPL(s, base)                                               \
-  [] {                                                                         \
-    /* Use a macro-like name to avoid shadowing warnings. */                   \
-    struct FMT_COMPILE_STRING_VISIBILITY_ATTRIBUTE 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 {                     \
-        return fmt::detail::compile_string_to_view<char_type>(s);              \
-      }                                                                        \
-    };                                                                         \
-    return FMT_COMPILE_STRING();                                               \
+#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_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 {        \
+        return fmt::detail::compile_string_to_view<char_type>(s); \
+      }                                                           \
+    };                                                            \
+    return FMT_COMPILE_STRING();                                  \
   }()
 
 /**