OK.
On Thu, Apr 5, 2018 at 5:06 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> We can't call maybe_apply_pragma_weak for structured binding decls
> at start_decl time, as that is too early, we don't have DECL_ASSEMBLER_NAME
> computed yet for them and because we don't have the corresponding decls
> around yet, we can't even compute it.
>
> This patch defers the maybe_apply_pragma_weak call from start_decl to
> cp_maybe_mangle_decomp where we just added the mangling the call needs.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2018-04-05 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/85208
> * decl.c (start_decl): For DECL_DECOMPOSITION_P decls, don't call
> maybe_apply_pragma_weak here...
> (cp_maybe_mangle_decomp): ... but call it here instead.
>
> * g++.dg/cpp1z/decomp42.C: New test.
>
> --- gcc/cp/decl.c.jj 2018-04-04 21:33:20.532639396 +0200
> +++ gcc/cp/decl.c 2018-04-05 13:29:39.128215719 +0200
> @@ -5090,7 +5090,7 @@ start_decl (const cp_declarator *declara
> }
>
> /* If #pragma weak was used, mark the decl weak now. */
> - if (!processing_template_decl)
> + if (!processing_template_decl && !DECL_DECOMPOSITION_P (decl))
> maybe_apply_pragma_weak (decl);
>
> if (TREE_CODE (decl) == FUNCTION_DECL
> @@ -7483,6 +7483,7 @@ cp_maybe_mangle_decomp (tree decl, tree
> for (unsigned int i = 0; i < count; i++, d = DECL_CHAIN (d))
> v[count - i - 1] = d;
> SET_DECL_ASSEMBLER_NAME (decl, mangle_decomp (decl, v));
> + maybe_apply_pragma_weak (decl);
> }
> }
>
> --- gcc/testsuite/g++.dg/cpp1z/decomp42.C.jj 2018-04-05 13:45:39.521220008
> +0200
> +++ gcc/testsuite/g++.dg/cpp1z/decomp42.C 2018-04-05 13:45:22.507220268
> +0200
> @@ -0,0 +1,9 @@
> +// PR c++/85208
> +// { dg-do compile { target c++11 } }
> +// { dg-require-weak "" }
> +// { dg-options "" }
> +
> +#pragma weak _ZDC1d1e1fE
> +struct A { int i, j, k; };
> +auto [a, b, c] = A (); // { dg-warning "structured bindings only available
> with" "" { target c++14_down } }
> +auto [d, e, f] = A (); // { dg-warning "structured bindings only available
> with" "" { target c++14_down } }
>
> Jakub
