[tz] [PROPOSED 1/7] Avoid undefined behavior if no Link lines

[Clive D.W. Feather]

Tom Lane via tz said:
> Jonathan Leffler via tz <tz at iana.org> writes:
> > I see nothing in the C standard specification of qsort() that says sorting
> > an array with zero members leads to undefined behaviour.
> 
> The C standard is silent on this (at least as of C99), but POSIX is
> absolutely unambiguous:
> 
>     If the nel argument has the value zero, the comparison function
>     pointed to by compar shall not be called and no rearrangement shall
>     take place.

But does it say whether the first argument is allowed to be NULL?

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Clive D.W. Feather          | If you lie to the compiler,
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