I don't think you'll find the culprit by comparing it with the 64-bit version of the current mingw. The previous version of 32-bit mingw successfully compiles the current revision of SBCL.
I don't think you'll find the culprit by comparing it with the 64-bit version of the current mingw. The previous version of 32-bit mingw successfully compiles the current revision of SBCL.