Close #18596: Support address sanity checking in clang/GCC

This patch appropriately marks known false alarms in the
small object allocator when address sanity checking is
enabled (patch contributed by Dhiru Kholia).

Misc/ACKS

@@ -650,6 +650,7 @@ Jim Kerr
 Magnus Kessler
 Lawrence Kesteloot
 Vivek Khera
+Dhiru Kholia
 Mads Kiilerich
 Jason Killen
 Jan Kim

Misc/NEWS

@@ -94,6 +94,13 @@ Documentation
 - Issue #17003: Unified the size argument names in the io module with common
   practice.
 
+Build
+-----
+
+- Issue #18596: Support the use of address sanity checking in recent versions
+  of clang and GCC by appropriately marking known false alarms in the small
+  object allocator. Patch contributed by Dhiru Kholia.
+
 Tools/Demos
 -----------
 

Objects/obmalloc.c

@@ -12,6 +12,24 @@ static void _PyObject_DebugDumpAddress(const void *p);
 static void _PyMem_DebugCheckAddress(char api_id, const void *p);
 #endif
 
+#if defined(__has_feature)  /* Clang */
+ #if __has_feature(address_sanitizer)  /* is ASAN enabled? */
+  #define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS \
+        __attribute__((no_address_safety_analysis)) \
+        __attribute__ ((noinline))
+ #else
+  #define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
+ #endif
+#else
+ #if defined(__SANITIZE_ADDRESS__)  /* GCC 4.8.x, is ASAN enabled? */
+  #define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS \
+        __attribute__((no_address_safety_analysis)) \
+        __attribute__ ((noinline))
+ #else
+  #define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
+ #endif
+#endif
+
 #ifdef WITH_PYMALLOC
 
 #ifdef MS_WINDOWS
@@ -1300,6 +1318,7 @@ _PyObject_Malloc(void *ctx, size_t nbytes)
 
 /* free */
 
+ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
 static void
 _PyObject_Free(void *ctx, void *p)
 {
@@ -1528,6 +1547,7 @@ _PyObject_Free(void *ctx, void *p)
  * return a non-NULL result.
  */
 
+ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
 static void *
 _PyObject_Realloc(void *ctx, void *p, size_t nbytes)
 {