OK.
On Thu, Jun 14, 2018 at 9:00 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> The following patch implements P0624R2, where stateless lambdas don't have
> deleted default ctor and copy assignment operator anymore.
>
> Tested on x86_64-linux with check-c++-all and libstdc++ testsuite, ok for
> trunk?
>
> 2018-06-14 Jakub Jelinek <ja...@redhat.com>
>
> P0624R2 - Default constructible and assignable stateless lambdas
> * method.c (synthesized_method_walk): For C++2a don't mark
> sfk_constructor or sfk_copy_assignment as deleted if lambda has
> no lambda-captures.
>
> * g++.dg/cpp2a/lambda1.C: New test.
> * g++.dg/cpp0x/lambda/lambda-ice2.C: Adjust expected diagnostics
> for -std=c++2a.
>
> --- gcc/cp/method.c.jj 2018-05-21 13:15:33.519575351 +0200
> +++ gcc/cp/method.c 2018-06-14 13:48:58.825585083 +0200
> @@ -1539,10 +1539,15 @@ synthesized_method_walk (tree ctype, spe
> {
> /* "The closure type associated with a lambda-expression has a deleted
> default constructor and a deleted copy assignment operator."
> - This is diagnosed in maybe_explain_implicit_delete. */
> + This is diagnosed in maybe_explain_implicit_delete.
> + In C++2a, only lambda-expressions with lambda-captures have those
> + deleted. */
> if (LAMBDA_TYPE_P (ctype)
> - && (sfk == sfk_constructor
> - || sfk == sfk_copy_assignment))
> + && (sfk == sfk_constructor || sfk == sfk_copy_assignment)
> + && (cxx_dialect < cxx2a
> + || LAMBDA_EXPR_CAPTURE_LIST (CLASSTYPE_LAMBDA_EXPR (ctype))
> + || LAMBDA_EXPR_DEFAULT_CAPTURE_MODE
> + (CLASSTYPE_LAMBDA_EXPR (ctype)) != CPLD_NONE))
> {
> *deleted_p = true;
> return;
> --- gcc/testsuite/g++.dg/cpp2a/lambda1.C.jj 2018-06-14 14:27:29.903602374
> +0200
> +++ gcc/testsuite/g++.dg/cpp2a/lambda1.C 2018-06-14 14:26:51.462571226
> +0200
> @@ -0,0 +1,58 @@
> +// P0624R2
> +// { dg-do compile { target c++11 } }
> +
> +#if __cplusplus >= 201402L
> +#define A auto
> +#else
> +#define A int
> +#endif
> +
> +void
> +f1 ()
> +{
> + auto greater = [](A x, A y) { return x > y; }; // { dg-message "a
> lambda closure type has a deleted (default constructor|copy assignment
> operator)" "" { target c++17_down } }
> + decltype (greater) gt; // { dg-error "use of deleted function" "" {
> target c++17_down } }
> + gt = greater; // { dg-error "use of deleted
> function" "" { target c++17_down } }
> +}
> +
> +void
> +f2 ()
> +{
> + auto greater = [&](A x, A y) { return x > y; }; // { dg-message "a
> lambda closure type has a deleted (default constructor|copy assignment
> operator)" }
> + decltype (greater) gt; // { dg-error "use of deleted function" }
> + gt = greater; // { dg-error "use of deleted
> function" }
> +}
> +
> +void
> +f3 ()
> +{
> + auto greater = [=](A x, A y) { return x > y; }; // { dg-message "a
> lambda closure type has a deleted (default constructor|copy assignment
> operator)" }
> + decltype (greater) gt; // { dg-error "use of deleted function" }
> + gt = greater; // { dg-error "use of deleted
> function" }
> +}
> +
> +void
> +f4 (int i)
> +{
> + auto greater = [i](A x, A y) { return x > y; }; // { dg-message "a
> lambda closure type has a deleted (default constructor|copy assignment
> operator)" }
> + decltype (greater) gt; // { dg-error "use of deleted function" }
> + gt = greater; // { dg-error "use of deleted
> function" }
> +}
> +
> +#if __cplusplus > 201703L
> +void
> +f5 ()
> +{
> + auto greater = [](auto x, auto y) constexpr { return x > y; };
> + decltype (greater) gt;
> + static_assert (!gt (1, 2));
> + static_assert (gt (4, 3));
> + static_assert (!gt (3.5, 3.75));
> + static_assert (gt (3.5, 3.25));
> + gt = greater;
> + static_assert (!gt (1, 2));
> + static_assert (gt (4, 3));
> + static_assert (!gt (3.5, 3.75));
> + static_assert (gt (3.5, 3.25));
> +}
> +#endif
> --- gcc/testsuite/g++.dg/cpp0x/lambda/lambda-ice2.C.jj 2014-05-15
> 11:58:42.000000000 +0200
> +++ gcc/testsuite/g++.dg/cpp0x/lambda/lambda-ice2.C 2018-06-14
> 14:32:03.760824236 +0200
> @@ -2,15 +2,15 @@
> // { dg-do compile { target c++11 } }
>
> template<typename F>
> -decltype(F()) run(F f) // { dg-message "note" }
> +decltype(F()) run(F f) // { dg-message "note" "" { target c++17_down } }
> {
> - return f();
> + return f(); // { dg-error "could not convert" "" { target c++2a } }
> }
>
> int main()
> {
> - auto l = []() { return 5; }; // { dg-message "lambda closure type" }
> + auto l = []() { return 5; }; // { dg-message "lambda closure type" "" {
> target c++17_down } }
>
> - run(l); // { dg-error "no match" }
> - // { dg-error "use of deleted function" "candidate explanation" { target
> *-*-* } 5 }
> + run(l); // { dg-error "no match" "" { target c++17_down } }
> + // { dg-error "use of deleted function" "candidate explanation" { target
> c++17_down } 5 }
> }
>
> Jakub
