[Bug c++/52707] New: [C++11] Deleted special member function prevent type being an aggregate

["daniel.kruegler at googlemail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52707

             Bug #: 52707
           Summary: [C++11] Deleted special member function prevent type
                    being an aggregate
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: daniel.kruegler@googlemail.com
                CC: jason@gcc.gnu.org


gcc 4.8.0 20120318 (experimental) in C++11 mode rejects the following code:

//---
struct A {
 int m;
 A() = delete;
};

A a = {1}; // line 6
//---

"6|error: could not convert '{1}' from '<brace-enclosed initializer list>' to
'A'|"

But according to N3290 (N3376 still the same) the user-declared, deleted
default-constructor should not prevent A from being an aggregate type and
aggregate initialization should happen here. The error text implies that A is
considered as a non-aggregate and no feasible constructor is found.

According to 8.4.2 p4:

"A function is user-provided if it is user-declared and not explicitly
defaulted or deleted on its first declaration."

and by 8.5.1 p1:

"An aggregate is [..] a class (Clause 9) with no user-provided constructors"

Thus, the deleted default constructor is not a user-provided constructor and
aggregate initialization should work.

This is due to DR 1135 which is already part of C++11:

http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1135