MinGW- Ignore return value from BOOST_INTERLOCKED_EXCHANGE

[mattyclarkson@…]

Warnings are created by MinGW for ignoring the return value in boost::detail::interlocked_read_acquire:

namespace boost
{
    namespace detail
    {
        inline long interlocked_read_acquire(long volatile* x) BOOST_NOEXCEPT
        {
            return BOOST_INTERLOCKED_COMPARE_EXCHANGE(x,0,0);
        }
        inline void* interlocked_read_acquire(void* volatile* x) BOOST_NOEXCEPT
        {
            return BOOST_INTERLOCKED_COMPARE_EXCHANGE_POINTER(x,0,0);
        }
        inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
        {
            BOOST_INTERLOCKED_EXCHANGE(x,value);
        }
        inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
        {
            BOOST_INTERLOCKED_EXCHANGE_POINTER(x,value);
        }
    }
}

My proposed fix it to cast the return value to void:

namespace boost
{
    namespace detail
    {
        inline long interlocked_read_acquire(long volatile* x) BOOST_NOEXCEPT
        {
            return BOOST_INTERLOCKED_COMPARE_EXCHANGE(x,0,0);
        }
        inline void* interlocked_read_acquire(void* volatile* x) BOOST_NOEXCEPT
        {
            return BOOST_INTERLOCKED_COMPARE_EXCHANGE_POINTER(x,0,0);
        }
        inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
        {
            (void)BOOST_INTERLOCKED_EXCHANGE(x,value);
        }
        inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
        {
            (void)BOOST_INTERLOCKED_EXCHANGE_POINTER(x,value);
        }
    }
}

It would also be possible to use static_cast<void>(...):

namespace boost
{
    namespace detail
    {
        inline long interlocked_read_acquire(long volatile* x) BOOST_NOEXCEPT
        {
            return BOOST_INTERLOCKED_COMPARE_EXCHANGE(x,0,0);
        }
        inline void* interlocked_read_acquire(void* volatile* x) BOOST_NOEXCEPT
        {
            return BOOST_INTERLOCKED_COMPARE_EXCHANGE_POINTER(x,0,0);
        }
        inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
        {
            static_cast<void>(BOOST_INTERLOCKED_EXCHANGE(x,value));
        }
        inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
        {
            static_cast<void>(BOOST_INTERLOCKED_EXCHANGE_POINTER(x,value));
        }
    }
}

[mattyclarkson@…]

Proposed cast to (void) patch

[viboes]

This code doesn't exists anymore.

From which version is the patch?

[mattyclarkson@…]

It was from 1.63 but the code has had a cast added to the pointer. The patch is now:

---
 boost/thread/win32/interlocked_read.hpp |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/boost/thread/win32/interlocked_read.hpp b/boost/thread/win32/interlocked_read.hpp
index 2ad3fe9..0a16407 100644
--- a/boost/thread/win32/interlocked_read.hpp
+++ b/boost/thread/win32/interlocked_read.hpp
@@ -61,11 +61,11 @@ namespace boost
         }
         inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
         {
-            BOOST_INTERLOCKED_EXCHANGE((long*)x,value);
+            (void)BOOST_INTERLOCKED_EXCHANGE((long*)x,value);
         }
         inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
         {
-            BOOST_INTERLOCKED_EXCHANGE_POINTER((void**)x,value);
+            (void)BOOST_INTERLOCKED_EXCHANGE_POINTER((void**)x,value);
         }
     }
 }
--
1.7.10.4

[viboes]

Closed as the code is not there anymore.