Handling argc==0 in the kernel

Linus's "no user regressions" policy covers *many* programs which are not Strictly Conforming POSIX Applications, so I'm not sure how that change in the standard is relevant. For example, anything that depends on Linux-specific interfaces, or on any implementation-defined behavior not specified by POSIX, is not a Strictly Conforming POSIX Application. (How many Strictly Conforming POSIX Applications are there in an average Linux installation, really?)

If you do claim to be a Strictly Conforming POSIX Application then you can't call exec with less than one argument. However, a Strictly Conforming POSIX Application may be *invoked* with zero arguments, and is required to handle that case as well to qualify as Strictly Conforming since POSIX does not specify that the argument list passed to main() will be non-empty and you can't assume every other program in the system is also Strictly Conforming.