I was able to get 6.4.1 code downloaded from SourceForge to compile with mingw.
I included these two directories in my path:
C:\MinGW\bin
C:\MinGW\msys\1.0\bin
I added these lines to makefile in the 6.4.1 core directory:
ifeq ($(PLATFORM),MINGW32_NT-6.2)
CLIPS_OS = LINUX
WARNINGS = -Wall -Wundef -Wpointer-arith -Wshadow -Wstrict-aliasing \
-Winline -Wredundant-decls -Waggregate-return
endif
The constant MINGW32_NT-6.2 may be different depending on which mingw installation you use.
I was able to determine this value for my installation by adding this line:
$(info $$PLATFORM is [${PLATFORM}])
after this line in the makefile:
PLATFORM = $(shell uname -s)
When I issued a make command, the platform was printed and I can then use this value in the prior ifeq command.