Re: [PATCH] C++: simplify output from suggest_alternatives_for

[Jason Merrill <jason@redhat.com>]

On Tue, Oct 9, 2018 at 1:19 PM David Malcolm <dmalcolm@redhat.com> wrote:
> +  /* Emulation of a "move" constructor, but really a copy
> +     constructor.  */
> +
> +  name_hint (const name_hint &other)
> +  : m_suggestion (other.m_suggestion),
> +    m_deferred (const_cast<name_hint &> (other).take_deferred ())
> +  {
> +  }
> +
> +  /* Emulation of "move" assigment, but really copy assignment.  */
> +
> +  name_hint& operator= (const name_hint &other)
> +  {
> +    m_suggestion = other.m_suggestion;
> +    m_deferred = const_cast<name_hint &> (other).take_deferred ();
> +    return *this;
> +  }
> +
> +  /* Take ownership of this name_hint's deferred_diagnostic, for use
> +     in chaining up deferred diagnostics.  */
> +  gnu::unique_ptr<deferred_diagnostic> take_deferred () { return move (m_deferred); }

Why do you want to propagate this hackery into name_hint?  I would
expect the defaulted special member functions to do the right thing
with m_deferred: in -std=c++98 the implicit copy ops call the
gnu::unique_ptr copy ops that actually move, and in -std=c++11 and up
we're calling the move constructor for std::unique_ptr, which does the
right thing.

This also doesn't limit the hack to C++98 mode the way unique-ptr.h does.

Jason