There are several ways to go here:

Option 1: Create a Custom Build Tool

Visual Studio 2005 and newer will let you register custom build tools. They tell the IDE how to transform files of one form (e.g. a .cpp file) into another form (e.g. an .obj file).

So far as I know, no one has done this yet for GCC. And, doing it yourself requires writing COM code, which is probably too deep a pool to dive into just for a single project. You'd have to have a compelling reason to take this project on.

You then have to manually adjust each project to tell it to use the custom build tool instead of the default, since you're using a file name extension (.cpp, probably) that Visual C++ already knows about. You'll run into trouble if you try to mix the VC++ and g++ compilers for a single executable built from multiple modules.

On the plus side, if you were looking to start an open source project, this sounds like a good one to me. I expect you'd quickly gather a big user base.

Option 2: Makefile Project

1. Start Visual Studio and say File > New Project.

2. In the Visual C++ section, select Makefile Project

3. Fill out the Makefile Project Wizard:

   • Build command line: make
   • Clean commands: make clean
   • Rebuild command line: make clean all

You can leave the Output (for debugging) field alone if you've named your executable after the project name and it lands where Visual Studio expects to find it.

Leave the rest of the fields alone unless you know what they are and why you want to change them. As an example, you might choose to pass a -D flag on the Preprocessor definitions line to get separate debug and release outputs. If you know you want this, you know how to set it up, so I'm not going to make this long answer even longer in order to explain it.

You'll be asked the same set of questions for the Release build. If you want to bother with separate debug and release builds, you'd make any changes here.

Having done all this, you still have to create the Makefile, and add a make.exe to your PATH. As with the debug vs. release question, going into that level of detail would push this answer off topic.

As ugly as this looks, it's still easier than creating custom build tools. Plus, you say you need to port to Unix eventually, so you're going to need that Makefile anyway.

Option 3: Cross-Platform Development

You say you want to port this program to Unix at some point, but that doesn't mean you must use GCC on Windows now. It is quite possible to write your program so that it builds under Visual C++ on Windows and GCC/Makefiles on *ix systems.

There are several tools that make this easier. One very popular option is CMake, which is available as an installation time option in newer versions of Visual Studio. There are many alternatives such as SCons and Bakefile.

EDIT Since not so recently by now, MinGW-w64 has "absorbed" one of the toolchain building projects. The downloads can be found here. The installer should work, and allow you to pick a version that you need.

Note the Qt SDK comes with the same toolchain. So if you are developing in Qt and using the SDK, just use the toolchain it comes with.

Another alternative that has up to date toolchains comes from... harhar... a Microsoft developer, none other than STL (Stephan T. Lavavej, isn't that a spot-on name for the maintainer of MSVC++ Standard Library!). You can find it here. It includes Boost.

Another option which is highly useful if you care for prebuilt dependencies is MSYS2, which provides a Unix shell (a Cygwin fork modified to work better with Windows pathnames and such), also provides a GCC. It usually lags a bit behind, but that is compensated for by its good package management system and stability. They also provide a functional Clang with libc++ if you care for such thing.

I leave the below for reference, but I strongly suggest against using MinGW.org, due to limitations detailed below. TDM-GCC (the MinGW-w64 version) provides some hacks that you may find useful in your specific situation, although I recommend using vanilla GCC at all times for maximum compatibility.

GCC for Windows is provided by two projects currently. They both provide a very own implementation of the Windows SDK (headers and libraries) which is necessary because GCC does not work with Visual Studio files.

1. The older mingw.org, which @Mat already pointed you to. They provide only a 32-bit compiler. See here for the downloads you need:

   • Binutils is the linker and resource compiler etc.
   • GCC is the compiler, and is split in core and language packages
   • GDB is the debugger.
   • runtime library is required only for mingw.org
   • You might need to download mingw32-make seperately.
   • For support, you can try (don't expect friendly replies) [email protected]

   Alternatively, download mingw-get and use that.

2. The newer mingw-w64, which as the name predicts, also provides a 64-bit variant, and in the future hopefully some ARM support. I use it and built toolchains with their CRT. Personal and auto builds are found under "Toolchains targetting Win32/64" here. They also provide Linux to Windows cross-compilers. I suggest you try a personal build first, they are more complete. Try mine (rubenvb) for GCC 4.6 to 4.8, or use sezero's for GCC 4.4 and 4.5. Both of us provide 32-bit and 64-bit native toolchains. These packages include everything listed above. I currently recommend the "MinGW-Builds" builds, as these are currently sanctioned as "official builds", and come with an installer (see above).

   For support, send an email to [email protected] or post on the forum via sourceforge.net.

Both projects have their files listed on sourceforge, and all you have to do is either run the installer (in case of mingw.org) or download a suitable zipped package and extract it (in the case of mingw-w64).

There are a lot of "non-official" toolchain builders, one of the most popular is TDM-GCC. They may use patches that break binary compatibility with official/unpatched toolchains, so be careful using them. It's best to use the official releases.