Some minor changes to compile bundled fmt propperly w. BUILD_SHARED_LIBS

Basically, libfmt also lacks support for propper generate_export_headers,
instead, some handwritten macros that only work on windows are used :-(
Personally, I think including dependencies in the build is always a bad idea,
but there might be good (Windows??) reasons for it. Anyhow, this is a rather
ugly fix to include the generate_export_headers into libfmt.

Signed-off-by: Matthias Schoepfer <matthias.schoepfer@ithinx.io>

CMakeLists.txt

@@ -7,6 +7,7 @@ cmake_minimum_required(VERSION 3.2)
 # Start spdlog project
 #---------------------------------------------------------------------------------------
 include(GNUInstallDirs)
+include(GenerateExportHeader)
 include(cmake/utils.cmake)
 include(cmake/ide.cmake)
 
@@ -99,8 +100,8 @@ endif()
 add_library(spdlog ${SPDLOG_SRCS} ${SPDLOG_ALL_HEADERS})
 add_library(spdlog::spdlog ALIAS spdlog)
 
+generate_export_header(spdlog)
 if (BUILD_SHARED_LIBS)
-  generate_export_header(spdlog)
   target_compile_definitions(spdlog PRIVATE SPDLOG_USE_EXPORT_HEADER)
   set_target_properties(spdlog PROPERTIES CXX_VISIBILITY_PRESET hidden)
   set_target_properties(spdlog PROPERTIES VISIBILITY_INLINES_HIDDEN 1)

include/spdlog/fmt/bundled/format.h

@@ -665,7 +665,7 @@ template <typename T = void> struct FMT_EXTERN_TEMPLATE_API basic_data {
   static const wchar_t wreset_color[5];
 };
 
-FMT_EXTERN template struct basic_data<void>;
+FMT_EXTERN template struct FMT_API basic_data<void>;
 
 // This is a struct rather than an alias to avoid shadowing warnings in gcc.
 struct data : basic_data<> {};

src/fmt.cpp

@@ -7,6 +7,7 @@
 // All rights reserved.
 
 #if !defined(SPDLOG_FMT_EXTERNAL)
+#include "spdlog/fmt/bundled/core.h"
 #include "spdlog/fmt/bundled/format-inl.h"
 
 FMT_BEGIN_NAMESPACE