From b7677b6f8482daad8374b2cf5430be2156308063 Mon Sep 17 00:00:00 2001
From: Daan <daanl@outlook.com>
Date: Fri, 8 Apr 2022 14:09:38 -0700
Subject: [PATCH] fix atomic warnings on clang14 (issue #571)

---
 include/mimalloc-atomic.h |  8 +++++++-
 src/init.c                | 10 +++++-----
 src/os.c                  |  2 +-
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/mimalloc-atomic.h b/include/mimalloc-atomic.h
index e07df84d..7ad5da58 100644
--- a/include/mimalloc-atomic.h
+++ b/include/mimalloc-atomic.h
@@ -23,10 +23,15 @@ terms of the MIT license. A copy of the license can be found in the file
 #define  _Atomic(tp)            std::atomic<tp>
 #define  mi_atomic(name)        std::atomic_##name
 #define  mi_memory_order(name)  std::memory_order_##name
+#if !defined(ATOMIC_VAR_INIT) || (__cplusplus >= 202002L) // c++20, see issue #571
+ #define MI_ATOMIC_VAR_INIT(x)  x
+#else
+ #define MI_ATOMIC_VAR_INIT(x)  ATOMIC_VAR_INIT(x)
+#endif
 #elif defined(_MSC_VER)
 // Use MSVC C wrapper for C11 atomics
 #define  _Atomic(tp)            tp 
-#define  ATOMIC_VAR_INIT(x)     x
+#define  MI_ATOMIC_VAR_INIT(x)  x
 #define  mi_atomic(name)        mi_atomic_##name
 #define  mi_memory_order(name)  mi_memory_order_##name
 #else
@@ -34,6 +39,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #include <stdatomic.h>
 #define  mi_atomic(name)        atomic_##name
 #define  mi_memory_order(name)  memory_order_##name
+#define  MI_ATOMIC_VAR_INIT(x)  ATOMIC_VAR_INIT(x)
 #endif
 
 // Various defines for all used memory orders in mimalloc
diff --git a/src/init.c b/src/init.c
index 854a2228..ad1e4d45 100644
--- a/src/init.c
+++ b/src/init.c
@@ -25,8 +25,8 @@ const mi_page_t _mi_page_empty = {
   0,       // used
   0,       // xblock_size
   NULL,    // local_free
-  ATOMIC_VAR_INIT(0), // xthread_free
-  ATOMIC_VAR_INIT(0), // xheap
+  MI_ATOMIC_VAR_INIT(0), // xthread_free
+  MI_ATOMIC_VAR_INIT(0), // xheap
   NULL, NULL
 };
 
@@ -91,7 +91,7 @@ mi_decl_cache_align const mi_heap_t _mi_heap_empty = {
   NULL,
   MI_SMALL_PAGES_EMPTY,
   MI_PAGE_QUEUES_EMPTY,
-  ATOMIC_VAR_INIT(NULL),
+  MI_ATOMIC_VAR_INIT(NULL),
   0,                // tid
   0,                // cookie
   { 0, 0 },         // keys
@@ -123,7 +123,7 @@ mi_heap_t _mi_heap_main = {
   &tld_main,
   MI_SMALL_PAGES_EMPTY,
   MI_PAGE_QUEUES_EMPTY,
-  ATOMIC_VAR_INIT(NULL),
+  MI_ATOMIC_VAR_INIT(NULL),
   0,                // thread id
   0,                // initial cookie
   { 0, 0 },         // the key of the main heap can be fixed (unlike page keys that need to be secure!)
@@ -325,7 +325,7 @@ bool _mi_is_main_thread(void) {
   return (_mi_heap_main.thread_id==0 || _mi_heap_main.thread_id == _mi_thread_id());
 }
 
-static _Atomic(size_t) thread_count = ATOMIC_VAR_INIT(1);
+static _Atomic(size_t) thread_count = MI_ATOMIC_VAR_INIT(1);
 
 size_t  _mi_current_thread_count(void) {
   return mi_atomic_load_relaxed(&thread_count);
diff --git a/src/os.c b/src/os.c
index 52939faa..f36f8480 100644
--- a/src/os.c
+++ b/src/os.c
@@ -983,7 +983,7 @@ static bool mi_os_resetx(void* addr, size_t size, bool reset, mi_stats_t* stats)
   if (p != start) return false;
 #else
 #if defined(MADV_FREE)
-  static _Atomic(size_t) advice = ATOMIC_VAR_INIT(MADV_FREE);
+  static _Atomic(size_t) advice = MI_ATOMIC_VAR_INIT(MADV_FREE);
   int oadvice = (int)mi_atomic_load_relaxed(&advice);
   int err;
   while ((err = mi_madvise(start, csize, oadvice)) != 0 && errno == EAGAIN) { errno = 0;  };