[basic.life] Giving less storage is still not UB

[languagelawyer]

Full name of submitter: Andrey Erokhin

Reference (section label): [basic.life]

Link to reflector thread (if any):

Issue description:

[basic.life]/1:

The lifetime of an object of type T begins when:
— storage with the proper alignment and size for type T is obtained

What about improper alignment and size? For alignment, there is [basic.align]/1:

Attempting to create an object ([intro.object]) in storage that does not meet the alignment requirements of the object's type is undefined behavior ([ub:basic.align.object.alignment]).

However, I couldn't find UB for size, meaning that in

alignas(int) unsigned char c;
auto pi = ::new(&c) int(0); // creates an int object whose lifetime just doesn't start?

Suggested resolution: