OK.
On Wed, Jan 25, 2017 at 4:07 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> As discussed in the PR, while lambda closure types are class types, it
> is implementation dependent on what those class types actually contain,
> allowing that to be decomposed is just weird.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2017-01-25 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/78896
> * decl.c (cp_finish_decomp): Disallow memberwise decomposition of
> lambda expressions.
>
> * g++.dg/cpp1z/decomp24.C: New test.
>
> --- gcc/cp/decl.c.jj 2017-01-25 17:17:51.000000000 +0100
> +++ gcc/cp/decl.c 2017-01-25 19:16:19.439879509 +0100
> @@ -7562,6 +7562,11 @@ cp_finish_decomp (tree decl, tree first,
> error_at (loc, "cannot decompose non-array non-class type %qT", type);
> goto error_out;
> }
> + else if (LAMBDA_TYPE_P (type))
> + {
> + error_at (loc, "cannot decompose lambda closure type %qT", type);
> + goto error_out;
> + }
> else
> {
> tree btype = find_decomp_class_base (loc, type, NULL_TREE);
> --- gcc/testsuite/g++.dg/cpp1z/decomp24.C.jj 2017-01-25 19:19:42.536296515
> +0100
> +++ gcc/testsuite/g++.dg/cpp1z/decomp24.C 2017-01-25 19:19:20.000000000
> +0100
> @@ -0,0 +1,11 @@
> +// PR c++/78896
> +// { dg-do compile { target c++11 } }
> +// { dg-options "" }
> +
> +int
> +foo ()
> +{
> + int a {10};
> + auto [b] { [&a](){} }; // { dg-error "cannot decompose lambda
> closure type" }
> + return b - a; // { dg-warning "decomposition
> declaration only available with" "" { target c++14_down } .-1 }
> +}
>
> Jakub
