coroutines: Build pointer initializers with nullptr_node [PR107768]

  From: Andrew Pinski <pinskia@gmail.com>

This is Andrew Pinski's patch, I just did testing, adjusted the test case and
provided the Changelog.
tested on x86-64-Darwin21,
OK for trunk?
Iain

--- >8 ---

The PR reports that using integer_zero_node triggers a warning for
-Wzero-as-null-pointer-constant which comes from compiler-generated code so
makes no sense to the end user.

Co-Authored-By: Iain Sandoe <iain@sandoe.co.uk>

	PR c++/107768

gcc/cp/ChangeLog:

	* coroutines.cc (coro_rewrite_function_body): Initialize pointers
	from nullptr_node.  (morph_fn_to_coro): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/coroutines/pr107768.C: New test.
---
 gcc/cp/coroutines.cc                       |  6 ++---
 gcc/testsuite/g++.dg/coroutines/pr107768.C | 26 ++++++++++++++++++++++
 2 files changed, 29 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/coroutines/pr107768.C
  

On 12/10/22 10:54, Iain Sandoe wrote:
> From: Andrew Pinski <pinskia@gmail.com>
> 
> This is Andrew Pinski's patch, I just did testing, adjusted the test case and
> provided the Changelog.
> tested on x86-64-Darwin21,
> OK for trunk?
> Iain

OK.

> --- >8 ---
> 
> The PR reports that using integer_zero_node triggers a warning for
> -Wzero-as-null-pointer-constant which comes from compiler-generated code so
> makes no sense to the end user.
> 
> Co-Authored-By: Iain Sandoe <iain@sandoe.co.uk>
> 
> 	PR c++/107768
> 
> gcc/cp/ChangeLog:
> 
> 	* coroutines.cc (coro_rewrite_function_body): Initialize pointers
> 	from nullptr_node.  (morph_fn_to_coro): Likewise.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/coroutines/pr107768.C: New test.
> ---
>   gcc/cp/coroutines.cc                       |  6 ++---
>   gcc/testsuite/g++.dg/coroutines/pr107768.C | 26 ++++++++++++++++++++++
>   2 files changed, 29 insertions(+), 3 deletions(-)
>   create mode 100644 gcc/testsuite/g++.dg/coroutines/pr107768.C
> 
> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
> index 3f23317a315..88d6c30d8b1 100644
> --- a/gcc/cp/coroutines.cc
> +++ b/gcc/cp/coroutines.cc
> @@ -4132,7 +4132,7 @@ coro_rewrite_function_body (location_t fn_start, tree fnbody, tree orig,
>     /* We will need to be able to set the resume function pointer to nullptr
>        to signal that the coroutine is 'done'.  */
>     tree zero_resume
> -    = build1 (CONVERT_EXPR, resume_fn_ptr_type, integer_zero_node);
> +    = build1 (CONVERT_EXPR, resume_fn_ptr_type, nullptr_node);
>   
>     /* The pointer to the destroy function.  */
>     tree var = coro_build_artificial_var (fn_start, coro_destroy_fn_id,
> @@ -4519,7 +4519,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>     tree ramp_body = push_stmt_list ();
>   
>     tree zeroinit = build1_loc (fn_start, CONVERT_EXPR,
> -			      coro_frame_ptr, integer_zero_node);
> +			      coro_frame_ptr, nullptr_node);
>     tree coro_fp = coro_build_artificial_var (fn_start, "_Coro_frameptr",
>   					    coro_frame_ptr, orig, zeroinit);
>     tree varlist = coro_fp;
> @@ -4754,7 +4754,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>   
>         gcc_checking_assert (same_type_p (fn_return_type, TREE_TYPE (grooaf)));
>         tree if_stmt = begin_if_stmt ();
> -      tree cond = build1 (CONVERT_EXPR, coro_frame_ptr, integer_zero_node);
> +      tree cond = build1 (CONVERT_EXPR, coro_frame_ptr, nullptr_node);
>         cond = build2 (EQ_EXPR, boolean_type_node, coro_fp, cond);
>         finish_if_stmt_cond (cond, if_stmt);
>         if (VOID_TYPE_P (fn_return_type))
> diff --git a/gcc/testsuite/g++.dg/coroutines/pr107768.C b/gcc/testsuite/g++.dg/coroutines/pr107768.C
> new file mode 100644
> index 00000000000..22d7074f261
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/coroutines/pr107768.C
> @@ -0,0 +1,26 @@
> +//  { dg-additional-options "-Wzero-as-null-pointer-constant -fsyntax-only" }
> +
> +#include <coroutine>
> +
> +struct task
> +{
> +    struct promise_type
> +    {
> +        task get_return_object() { return {}; }
> +        std::suspend_never initial_suspend() { return {}; }
> +        std::suspend_never final_suspend() noexcept { return {}; }
> +        void return_void() {}
> +        void unhandled_exception() {}
> +    };
> +};
> +
> +task resuming_on_new_thread(void)
> +{
> +    struct awaitable
> +    {
> +        bool await_ready() { return false; }
> +        void await_suspend(std::coroutine_handle<> h)         {         }
> +        void await_resume() {}
> +    };
> +    co_await awaitable{};
> +}