g++ doesn't recognize the file format of a dll

Question

I am on Windows, and I am using the version of g++ that comes with mingw-64. I have a file on my computer called lua51.dll. When I try to run the following command :

g++ -shared -fPIC -o stuff.dll -llua51 stuff.cpp

I get the following error:

C:/Program Files/LOVE/lua51.dll: file not recognized: File format not recognized
collect2.exe: error: ld returned 1 exit status
make: *** [main] Error 1

How can I fix this? Please let me know if more information is needed; I am a complete beginner to compilation.

Answer 1

This is an issue you get when you try to include a 64-bit library when running a 32-bit version of g++ or even gcc.

I thought that that the version of g++.exe that comes with mingw-64 would produce 64-bit code, but it turns out this isn't true; it still only produces 32-bit code. In my case, lua51.dll is 64-bit, which is an issue since I was using the version of g++ that produces 32-bit code.

Instead, you need to use x86_64-w64-mingw32-g++.exe, which can be found in the same folder as g++.exe. This is the version of g++ that will produce 64-bit code.