C++/c-common PATCH for c++/35688 (wrong visibility of template instantiation)

[Joseph S. Myers]

On Sun, 6 Nov 2011, Jason Merrill wrote:

> The function constrain_visibility_for_template tries to set the visibility of
> a template instantiation properly by giving it the minimum visibility of the
> template itself and the template arguments.  But this PR points out that we
> were failing to do that in the case that the template is within a namespace
> with a visibility attribute, because then it gets DECL_VISIBILITY_SPECIFIED.
> This patch fixes that by re-using some of the C front end's visibility code,
> so that we can further constrain visibility on a decl with
> DECL_VISIBILITY_SPECIFIED so long as it doesn't actually have a visibility
> attribute.
> 
> Joseph, I assume you have no objection to the c-common refactoring?

It's fine with me.

-- 
Joseph S. Myers
joseph@codesourcery.com