I'm trying to apply this patch to GCC on MinGW to get it to compile GDC 2, but I don't know how. (I'm still new to the internals of GCC, and even to *nix tools in general.) I know there's the patch command but I can't figure out how to use it, and I don't even know if I have enough information for this.
How do I apply the patch for GCC?
By default GNU Patch can be used by feeding a patch file to it from stdin (console input), e.g.:
patch < file.patch
There are many switches and options patch can use, the functionality is described here:
http://www.rtr.com/winpak/Documentation/patch.htm
http://www.gnu.org/software/diffutils/manual/html_mono/diff.html#Invoking%20patch
patch and diff work hand in hand. A small demonstration is found on wikipedia.