Hmm, although ARCH_FLAG is added for universal binary, CFLAGS has never been used from the beginning 0af44e7 (not removed at any moment). It sounds fine to try using pass CFLAGS if it makes msys1 build succeed.

For future information, what was in your $(CFLAGS)? Can how transform_mjit_header.rb command outputs are changed before and after this patch?

I've just saw your comment in https://bugs.ruby-lang.org/issues/14964. So, -msse4.1 matters, right?

yes, FYI the same problem is on msys2. But only if you enable sse4 support via CFLAGS like -msse4.2 or in my case -march=native

if miniruby is compiled with this flag, running transform_mjit_header.rb without these flags causes errors like error: implicit declaration of function '__builtin_ia32_crc32qi'

according to the documentation
https://gcc.gnu.org/onlinedocs/gcc/x86-Built-in-Functions.html

The following built-in functions are available when -msse4.2 is used.
unsigned int __builtin_ia32_crc32qi (unsigned int, unsigned char)
....

these functions aren't available because -msse4.2 is ignored

if miniruby is compiled with this flag

I believe miniruby is not so related to the error here, just compiler flags used inside transform_mjit_header.rb matters.

Anyway, let me merge this and check if it works in other environments. Possibly I'll change passed-through flags to only -m* flags, but I'll try this as is first.

thanks for your prompt response. I retested on ubuntu with custom flags and it seems to be ok.