First of all, I would like to thank you for your contribution to the open source!
I found some problem with m4 1.4.18. It has been built by clang 13 with "-g -fsanitize=address,undefined -fno-omit-frame-pointer -fsanitize-address-use-after-scope -fno-sanitize-recover=all"
And we have an error:
obstack.c:139:35: runtime error: applying non-zero offset 107820858999056 to null pointer
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior obstack.c:139:35 in
I think, it is so and for 1.4.19