Re: Switch to std::atomic?

[John W. Eaton]

On 9/26/19 4:25 PM, Dmitri A. Sergatskov wrote:

> There are some errors on clang compiles, e.g.:
>
> http://buildbot.octave.org:8010/#/builders/9/builds/1121
>
>
>
> ../src/liboctave/util/oct-atomic.c:34:3: error: address argument to
> atomic operation must be a pointer to _Atomic type ('octave_idx_type
> *' (aka 'long *') invalid)
>    atomic_fetch_add (x, 1);
>    ^                 ~
> /usr/lib64/clang/8.0.0/include/stdatomic.h:146:43: note: expanded from
> macro 'atomic_fetch_add'
> #define atomic_fetch_add(object, operand)
> __c11_atomic_fetch_add(object, operand, __ATOMIC_SEQ_CST)
>                                            ^                      ~~~~~~
> ../src/liboctave/util/oct-atomic.c:42:3: error: address argument to
> atomic operation must be a pointer to _Atomic type ('octave_idx_type
> *' (aka 'long *') invalid)
>    atomic_fetch_sub (x, 1);
>    ^                 ~
> /usr/lib64/clang/8.0.0/include/stdatomic.h:149:43: note: expanded from
> macro 'atomic_fetch_sub'
> #define atomic_fetch_sub(object, operand)
> __c11_atomic_fetch_sub(object, operand, __ATOMIC_SEQ_CST)
>                                            ^                      ~~~~~~
> 2 errors generated.
> make[2]: *** [Makefile:16937: liboctave/util/libutil_la-oct-atomic.lo] Error 1
>
>
> Dmitri.
> --

Is the following change OK or is this a dangerous or invalid cast?

--- a/liboctave/util/oct-atomic.c
+++ b/liboctave/util/oct-atomic.c
@@ -31,7 +31,7 @@ along with Octave; see the file COPYING.
 octave_idx_type
 octave_atomic_increment (octave_idx_type *x)
 {
-  atomic_fetch_add (x, 1);
+  atomic_fetch_add ((_Atomic octave_idx_type *) x, 1);

   return *x;
 }
@@ -39,7 +39,7 @@ octave_atomic_increment (octave_idx_type
 octave_idx_type
 octave_atomic_decrement (octave_idx_type *x)
 {
-  atomic_fetch_sub (x, 1);
+  atomic_fetch_sub ((_Atomic octave_idx_type *) x, 1);

   return *x;
 }

jwe