[Bug c++/53330] New: new() operator can return NULL on a zero-length allocation

[kilobyte at angband dot pl]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53330

             Bug #: 53330
           Summary: new() operator can return NULL on a zero-length
                    allocation
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: kilobyte@angband.pl


Created attachment 27386
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27386
test case

While in general C++ disallows zero-length arrays, they are explicitly allowed
by the new() operator (C++ 3.7.4.1.2), with a guarantee that such an allocation
will always return an unique non-null pointer.

This worked correctly in 4.6 and before (and clang, and MSVC, ...), 4.7.0
(Debian 4.7.0-8) and trunk@187013 return null if elements of the array have a
constructor and have sizeof() > 0 themselves.  For simple types or structs, all
is ok.

Also, if there's a constructor (no regards for sizeof(element)) and the array
length is known at compile time, -Wuninitialized returns incorrect diagnostics
that the returned value is uninitialized.