MSVS 2015 building a dll - unresolved external symbol _main in invoke_main in MSVCRTD.lib (exe_main.obj)

Question

I want to compile a DLL and use it in my project. (It has to be a DLL because I am using Windows Hooks and it has to be loaded at runtime). For more information, it uses Allegro 5 from Nuget.

I am getting the following error when I try to build my DLL:

LNK2019 unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ) in file MSVCRTD.lib (exe_main.obj)

I've recreated the project several times now due to configuration issues. My latest iteration is Win32 Windowed Application and DLL being built with the Multi Threaded Debug DLL runtime - I have tried all the other options and none of the rest work.

I don't understand why it's searching for main: it's a DLL. I haven't provided a DLLMain as I understood it's not necessary because MSVS will provide it for you.

How would I resolve this build issue when trying to compile my DLL?

EDIT The solution was to #define ALLEGRO_NO_MAGIC_MAIN. The Allegro library expects a main function unless you define ALLEGRO_NO_MAGIC_MAIN. Problem solved.

Answer 1

The solution was to #define ALLEGRO_NO_MAGIC_MAIN before including Allegro 5 headers. Allegro expects to see a main function, and that is why the linker was looking for it.