build: Update GENERATE_EXPORT_HEADER to automatically define module_EXPORTS

build-support/cmake-format-modules.yaml

@@ -12,7 +12,7 @@ additional_commands:
             DEFINITIONS : '*'
 
     build_lib:
-        flags: [IGNORE_PCH]
+        flags: [IGNORE_PCH, GENERATE_EXPORT_HEADER]
         kwargs:
             LIBNAME : '1'
             SOURCE_FILES : '*'

build-support/cmake-format.yaml

@@ -12,7 +12,7 @@ additional_commands:
             DEFINITIONS : '*'
 
     build_lib:
-        flags: [IGNORE_PCH]
+        flags: [IGNORE_PCH, GENERATE_EXPORT_HEADER]
         kwargs:
             LIBNAME : '1'
             SOURCE_FILES : '*'

build-support/custom-modules/ns3-module-macros.cmake

@@ -194,6 +194,13 @@ function(build_lib)
     set(export_dest ${CMAKE_HEADER_OUTPUT_DIRECTORY}/${BLIB_LIBNAME}-export.h)
     file(COPY_FILE ${export_file} ${export_dest})
     install(FILES ${export_file} DESTINATION include/ns3 COMPONENT Headers)
+
+    # In case building on Visual Studio
+    if(${MSVC})
+      target_compile_definitions(
+        ${BLIB_LIBNAME} PRIVATE ${BLIB_LIBNAME}_EXPORTS
+      )
+    endif()
   endif()
 
   # Reuse PCH
@@ -361,7 +368,7 @@ endfunction()
 
 function(build_lib_export_definitions_as_interface_definitions libname)
   get_target_property(target_definitions ${libname} COMPILE_DEFINITIONS)
-  if(${target_definitions} STREQUAL "target_definitions-NOTFOUND")
+  if("${target_definitions}" STREQUAL "target_definitions-NOTFOUND")
     set(target_definitions)
   endif()
   get_directory_property(dir_definitions COMPILE_DEFINITIONS)