mach, hurd: Cast through uintptr_t

When casting between a pointer and an integer of a different size, GCC
emits a warning (which is escalated to a build failure by -Werror).
Indeed, if what you start with is a pointer, which you then cast to a
shorter integer and then back again, you're going to cut off some bits
of the pointer.

But if you start with an integer (such as mach_port_t), then cast it to
a longer pointer (void *), and then back to a shorter integer, you are
fine. To keep GCC happy, cast through an intermediary uintptr_t, which
is always the same size as a pointer.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230212111044.610942-4-bugaevc@gmail.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/hurd/port-cleanup.c b/hurd/port-cleanup.c
index 08ab3d47cb..ad43b83013 100644
--- a/hurd/port-cleanup.c
+++ b/hurd/port-cleanup.c
@@ -26,7 +26,8 @@
 void
 _hurd_port_cleanup (void *cleanup_data, jmp_buf env, int val)
 {
-  __mach_port_deallocate (__mach_task_self (), (mach_port_t) cleanup_data);
+  mach_port_t port = (mach_port_t) (uintptr_t) cleanup_data;
+  __mach_port_deallocate (__mach_task_self (), port);
 }
 
 /* We were cancelled while using a port, and called from the cleanup unwinding.