Another FWIW, building on i386 with -O1 instead of -O2 and dropping -fno-strict-aliasing is successful.
Where can one find the differences between -O1 and -O2 in GCC 7? What changed between GCC 6 and 7 would be useful too. --- a/debian/rules +++ b/debian/rules @@ -7,7 +7,10 @@ include /usr/share/dpkg/default.mk -export DEB_CFLAGS_MAINT_APPEND = -fno-strict-aliasing +ifneq (,$(filter $(DEB_HOST_ARCH),i386)) + export DEB_CFLAGS_MAINT_STRIP=-O2 + export DEB_CFLAGS_MAINT_APPEND=-O1 +endif %: dh $@