expect fails to compile with compiler flags which elevate common string formatting issues into an error (-Wformat -Wformat-security -Werror=format-security).
Setting assignee to recipe maintainer. Alexander, please update estimate, target, etc. to suit your workload.
Maybe before 2.3 is out. 100% busy with dnf now.
No problem. Should've included reproduction steps much sooner: to observe the failures comment out the recipe's SECURITY_STRINGFORMAT entry in security_cflags.inc and build the recipe with a configuration that utilises security_cflags (i.e. the poky-lsb distro).