[Bug c++/67981] New: new expression with zero size not diagnosed

["msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67981

            Bug ID: 67981
           Summary: new expression with zero size not diagnosed
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

Continuing with new expression conformance issues (bug 67913 and bug 67917):

In 5.3.4, p6, C++ 11 says that "Every constant-expression in a
noptr-new-declarator shall be an integral constant expression (5.19) and
evaluate to a strictly positive value."  C++ 14 has an equivalent requirement.

The following test case shows that gcc doesn't implement this constraint and
accepts a constant expression with a zero value:

$ echo "void* f () { return new char [0]; }" | g++ -Wall -Werror -Wextra
-Wpedantic -c -std=c++11 -xc++ -