[Bug c++/28956] New: Illegal array initialization accepted

[ppluzhnikov at charter dot net]

Consider:

struct Foo {
  Foo(); // comment out -> g++ fails with "error: invalid initializer"
};

void fn()
{
  Foo f[2];
  Foo g[2] = f;
}

The test above is accepted by g++ (tried 3.4.6, 4.0.0, 4.1.1 and 4.2-20060902).

EDG fails with:
$ edgcpfe pp.cpp
"pp.cpp", line 8: error: initialization with "{...}" expected for aggregate
          object
      Foo g[2] = f;
                 ^

1 error detected in the compilation of "pp.cpp".

Here is the original test case (also accepted by all versions of g++):

template <class T, class U>
struct pair {
    pair(const T& t, const U& u) : first(t), second(u) { }
    T first;
    U second;
};

struct Foo {
    Foo(); // comment out -> g++ fails with 
           // "error: ISO C++ forbids assignment of arrays"
};

int main()
{
    Foo f[2];
    pair<int, Foo[2]> p (1, f);
    return 0;
}

And analysis of it by William M. (Mike) Miller | Edison Design Group, Inc.:

> Could you please confirm that this is a g++ bug?

Yes, it's a bug.  The Standard (12.6.2 paragraph 3) defines an initialization
like "second(u)" to be direct-initialization as described in section 8.5. 
Section 8.5 paragraph 14 says that initialization of an array object is handled
in section 8.5.1. However, 8.5.1 does not provide for any way of initializing
an array from another array (except for the special case of a string literal,
8.5.2).  Arrays can only be initialized to a value using the brace notation,
which is not permitted in a mem-initializer.


-- 
           Summary: Illegal array initialization accepted
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ppluzhnikov at charter dot net
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28956