Re: [PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[Jason Merrill <jason at redhat dot com>]

On 8/14/19 10:39 AM, David Malcolm wrote:
> On Wed, 2019-08-14 at 12:02 +0100, Jonathan Wakely wrote:
> > On 13/08/19 16:07 -0400, Jason Merrill wrote:
> > > On 8/13/19 9:32 AM, Jonathan Wakely wrote:
> > > >      * g++.dg/lookup/missing-std-include-6.C: Don't check
> > > > make_unique in
> > > >      test that runs for C++11.
> > >
> > > I'm not comfortable removing this test coverage entirely.  Doesn't
> > > it
> > > give a useful diagnostic in C++11 mode as well?
> >
> > It does:
> >
> > mu.cc:3:15: error: 'make_unique' is not a member of 'std'
> >      3 | auto p = std::make_unique<int>();
> >        |               ^~~~~~~~~~~
> > mu.cc:3:15: note: 'std::make_unique' is only available from C++14
> > onwards
> > mu.cc:3:27: error: expected primary-expression before 'int'
> >      3 | auto p = std::make_unique<int>();
> >        |                           ^~~
> >
> > So we can add it to g++.dg/lookup/missing-std-include-8.C instead,
> > which runs for c++98_only and checks for the "is only available for"
> > cases. Here's a patch doing that.
>
> FWIW this eliminates the testing that when we do have C++14 onwards,
> that including <memory> is suggested.
>
> Maybe we need a C++14-onwards missing-std-include-* test, and to move
> the existing test there?  (and to add the new test for before-C++-14)

We can also check for different messages in different std modes, i.e.

{ dg-message "one" "" { target c++11_down } .-1 }
{ dg-message "two" "" { target c++14 } .-2 }

Jason