can't have const value_initialized members

[Chris Jefferson]

Code like:

const value_initialized<int> x;

Is invalid in clang and comeau, as they correctly (I believe) reject default initialization of const objects without a user-provided default constructor.

The attached patch adds a default constructor, along with a copy constructor and operator=, just for consistency. It makes clang++ pass all tests for utility, and does not make g++ fail any.

[Chris Jefferson]

Patch to value_init.hpp

[niels_dekker]

The regression failures were caused by my commit [61883], which reimplemented value_initialized<T> in terms of initialized<T>. See also: [boost] Patch to value_initialized, May 13, 2010.

[niels_dekker]

(In [61947]) Hopefully fixed value_initialized compile errors on clang and comeau (strict mode) reported by Christopher Jefferson, see #4213

[niels_dekker]

While yesterday, the test output of value_init_test had compile errors for clang-darwin-2.0 (error: default initialization of an object of const type 'boost::value_initialized<int> const' requires a user-provided default constructor), this morning the errors are gone. (Looking at http://www.boost.org/development/tests/trunk/developer/utility_.html) So [61947] resolved the issue. Thanks, Chris!