[CMake] Enable Windows shared libs support.

Everything works automatically except for global symbols where some manual work is required. See the BuildInfo example.

BaseLib/BuildInfo.h

@@ -13,29 +13,31 @@
 
 #include <string>
 
+#include "baselib_export.h"
+
 namespace BaseLib
 {
 
 namespace BuildInfo
 {
-    extern const std::string build_timestamp;
+    extern BASELIB_EXPORT const std::string build_timestamp;
 
-    extern const std::string cmake_cxx_compiler;
-    extern const std::string cmake_cxx_flags;
-    extern const std::string cmake_cxx_flags_release;
-    extern const std::string cmake_cxx_flags_debug;
+    extern BASELIB_EXPORT const std::string cmake_cxx_compiler;
+    extern BASELIB_EXPORT const std::string cmake_cxx_flags;
+    extern BASELIB_EXPORT const std::string cmake_cxx_flags_release;
+    extern BASELIB_EXPORT const std::string cmake_cxx_flags_debug;
 
-    extern const std::string git_version_sha1;
-    extern const std::string git_version_sha1_short;
+    extern BASELIB_EXPORT const std::string git_version_sha1;
+    extern BASELIB_EXPORT const std::string git_version_sha1_short;
 
-    extern const std::string git_describe;
-    extern const std::string ogs_version;
+    extern BASELIB_EXPORT const std::string git_describe;
+    extern BASELIB_EXPORT const std::string ogs_version;
 
-    extern const std::string source_path;
-    extern const std::string geo_xml_schema_path;
-    extern const std::string app_xml_schema_path;
-    extern const std::string data_path;
-    extern const std::string data_binary_path;
-    extern const std::string tests_tmp_path;
+    extern BASELIB_EXPORT const std::string source_path;
+    extern BASELIB_EXPORT const std::string geo_xml_schema_path;
+    extern BASELIB_EXPORT const std::string app_xml_schema_path;
+    extern BASELIB_EXPORT const std::string data_path;
+    extern BASELIB_EXPORT const std::string data_binary_path;
+    extern BASELIB_EXPORT const std::string tests_tmp_path;
 }
 }

BaseLib/CMakeLists.txt

@@ -12,12 +12,16 @@ list(APPEND SOURCES "${CMAKE_CURRENT_BINARY_DIR}/BuildInfo.cpp" BuildInfo.h)
 # Create the library
 add_library(BaseLib ${SOURCES})
 
+include(GenerateExportHeader)
+generate_export_header(BaseLib)
+target_include_directories(BaseLib PUBLIC ${CMAKE_CURRENT_BINARY_DIR})
+
 set_target_properties(BaseLib PROPERTIES LINKER_LANGUAGE CXX)
 
 target_link_libraries(BaseLib PUBLIC logog)
 
 if(MSVC)
-    target_link_libraries(BaseLib PRIVATE WinMM) # needed for timeGetTime
+    target_link_libraries(BaseLib PUBLIC WinMM) # needed for timeGetTime
 endif()
 
 if(Qt5XmlPatterns_FOUND)

scripts/cmake/CompilerSetup.cmake

@@ -29,10 +29,13 @@ elseif(${CMAKE_CXX_COMPILER_ID} STREQUAL "MSVC")
     set(COMPILER_IS_MSVC TRUE CACHE INTERNAL "")
 endif() # CMAKE_CXX_COMPILER_ID
 
-# When static libraries are used in some shared libraries it is required that
-# also the static libraries have position independent code.
 if(BUILD_SHARED_LIBS)
+    # When static libraries are used in some shared libraries it is required
+    # that also the static libraries have position independent code.
     set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
+
+    # Enable Windows DLL support.
+    set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
 endif()
 
 # Set additional user-given compiler flags