atomic: Fix -Wincompatible-pointer-types-discards-qualifiers

atomic/unix/builtins.c:117:38: warning: passing 'void **' to parameter of type 'volatile void **' discards qualifiers in nested pointer types [-Wincompatible-pointer-types-discards-qualifiers]
    __atomic_compare_exchange_n(mem, (void **)&cmp, ptr, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
                                     ^~~~~~~~~~~~~

This warning is weird, because 'volatile void **' is not a thing usually, it
happens on macos in apr-1.x, where apr_atomic_casptr() is (ill-)defined as:
  APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *ptr, const void *cmp);
but not on trunk's:
  APR_DECLARE(void*) apr_atomic_casptr(void *volatile *mem, void *ptr, const void *cmp);
The mark clearly indicates that (void **)&cmp is the culprit though (compiler bug?).

Let's see if using the generic (void *) cast helps, the goal of the (void **)
cast was to remove constantness only (__atomic_compare_exchange_n will modify
the pointer on stack, but not the pointed to value), (void *) will do that too
without any volatile qualifier issue possibly.


Merge r1902233 from trunk.
Submitted by: ylavic


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.8.x@1902234 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 1 insertions, 1 deletions

diff --git a/atomic/unix/builtins.c b/atomic/unix/builtins.c
index 22b828c3c..6aaae1ba2 100644
--- a/atomic/unix/builtins.c
+++ b/atomic/unix/builtins.c
@@ -114,7 +114,7 @@ APR_DECLARE(apr_uint32_t) apr_atomic_xchg32(volatile apr_uint32_t *mem, apr_uint
 APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *ptr, const void *cmp)
 {
 #if HAVE__ATOMIC_BUILTINS
-    __atomic_compare_exchange_n(mem, (void **)&cmp, ptr, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+    __atomic_compare_exchange_n(mem, (void *)&cmp, ptr, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
     return (void *)cmp;
 #else
     return (void *)__sync_val_compare_and_swap(mem, (void *)cmp, ptr);