From 087bfe2b31d68ef74adda9615c6f58b17b09c334 Mon Sep 17 00:00:00 2001
From: denchat <19730041+denchat@users.noreply.github.com>
Date: Tue, 13 Apr 2021 11:42:15 +0700
Subject: [PATCH] Create separated FMT_INSTANTIATION_DEF_API

 Create a separated FMT_INSTANTIATION_DEF_API

Create separated FMT_INSTANTIATION_DEF_API and FMT_INSTANTIATION_DECL_API
to fix dllexport requirement differences between clang and msvc.

- clang:  mark dllexport on extern template (template instantiation declaration) in format.h
- msvc:  mark dllexport on template instantiation definition in format.cc
---
 include/fmt/core.h | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/include/fmt/core.h b/include/fmt/core.h
index 4145bd9e..38a928ad 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -223,8 +223,19 @@
 #ifndef FMT_EXTERN_TEMPLATE_API
 #  define FMT_EXTERN_TEMPLATE_API
 #endif
-#ifndef FMT_INSTANTIATION_DECL_API
-#  define FMT_INSTANTIATION_DECL_API FMT_API
+#ifndef FMT_INSTANTIATION_DECL_API // clang marks dllexport at extern template.
+#  ifndef _MSC_VER
+#    define FMT_INSTANTIATION_DECL_API FMT_API
+#  else
+#    define FMT_INSTANTIATION_DECL_API
+#  endif
+#endif
+#ifndef FMT_INSTANTIATION_DEF_API // msvc marks dllexport at the definition itself.
+#  ifndef _MSC_VER
+#    define FMT_INSTANTIATION_DEF_API
+#  else
+#    define FMT_INSTANTIATION_DEF_API FMT_API
+# endif
 #endif
 
 #ifndef FMT_HEADER_ONLY