[Moved to DR at the May, 2015 meeting.]

Proposed resolution (November, 2014):

Change 6.7.6.4 [basic.stc.auto] paragraph 3 as follows:

If a variable with automatic storage duration has initialization or a destructor with side effects, it an implementation shall not be destroyed destroy it before the end of its block, nor shall it be eliminated eliminate it as an optimization, even if it appears to be unused, except that a class object or its copy/move may be eliminated as specified in 11.4.5.3 [class.copy.ctor].

According to 6.7.6.4 [basic.stc.auto] paragraph 3,

If a variable with automatic storage duration has initialization or a destructor with side effects, it shall not be destroyed before the end of its block, nor shall it be eliminated as an optimization even if it appears to be unused, except that a class object or its copy/move may be eliminated as specified in 11.4.5.3 [class.copy.ctor].

This is intended to be a requirement for the implementation, but it could be read as prohibiting the reuse of the storage of an automatic variable by the program using a placement new-expression.