On Sun, Feb 02, 2025 at 11:14:55AM +0100, Jakub Jelinek wrote:
> Hi!
>
> As mentioned in the PR, this pedwarni is desirable for the implicit or
> explicit capturing of structured bindings in C++17, but in the case of
> init-captures the initializer is just some expression and that can include
> structured bindings.
>
> So, the following patch limits the warning to non-explicit_init_p.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
LGTM, sorry for missing the !explicit_init_p check.
> 2025-02-02 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/118719
> * lambda.cc (add_capture): Only pedwarn about capturing structured
> binding if !explicit_init_p.
>
> * g++.dg/cpp1z/decomp63.C: New test.
>
> --- gcc/cp/lambda.cc.jj 2025-01-24 17:37:49.004457905 +0100
> +++ gcc/cp/lambda.cc 2025-01-31 23:47:08.907034696 +0100
> @@ -613,7 +613,7 @@ add_capture (tree lambda, tree id, tree
> return error_mark_node;
> }
>
> - if (cxx_dialect < cxx20)
> + if (cxx_dialect < cxx20 && !explicit_init_p)
> {
> auto_diagnostic_group d;
> tree stripped_init = tree_strip_any_location_wrapper (initializer);
> --- gcc/testsuite/g++.dg/cpp1z/decomp63.C.jj 2025-01-31 23:54:15.480699418
> +0100
> +++ gcc/testsuite/g++.dg/cpp1z/decomp63.C 2025-01-31 23:53:02.998578507
> +0100
> @@ -0,0 +1,18 @@
> +// PR c++/118719
> +// { dg-do compile { target c++11 } }
> +// { dg-options "" }
> +
> +int
> +main ()
> +{
> + int a[] = { 42 };
> + auto [x] = a; // { dg-warning
> "structured bindings only available with" "" { target c++14_down } }
> + // { dg-message "declared here"
> "" { target c++17_down } .-1 }
> + [=] () { int b = x; (void) b; }; // { dg-warning "captured
> structured bindings are a C\\\+\\\+20 extension" "" { target c++17_down } }
> + [&] () { int b = x; (void) b; }; // { dg-warning "captured
> structured bindings are a C\\\+\\\+20 extension" "" { target c++17_down } }
> + [x] () { int b = x; (void) b; }; // { dg-warning "captured
> structured bindings are a C\\\+\\\+20 extension" "" { target c++17_down } }
> + [&x] () { int b = x; (void) b; }; // { dg-warning "captured
> structured bindings are a C\\\+\\\+20 extension" "" { target c++17_down } }
> + [x = x] () { int b = x; (void) b; }; // { dg-warning "lambda
> capture initializers only available with" "" { target c++11_only } }
> + [y = x] () { int b = y; (void) b; }; // { dg-warning "lambda
> capture initializers only available with" "" { target c++11_only } }
> + [y = x * 2] () { int b = y; (void) b; }; // { dg-warning "lambda capture
> initializers only available with" "" { target c++11_only } }
> +}
>
> Jakub
>
Marek
