--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/Analysis/retain-count-alloc.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,37 @@
+// RUN: %clang_analyze_cc1 \
+// RUN:  -analyzer-checker=core,unix.Malloc \
+// RUN:  -verify %s
+
+// expected-no-diagnostics: We do not model Integer Set Library's retain-count
+//                          based allocation. If any of the parameters has an
+//                          '__isl_' prefixed macro definition we escape every
+//                          of them when we are about to 'free()' something.
+
+#define __isl_take
+#define __isl_keep
+
+struct Object { int Ref; };
+void free(void *);
+
+Object *copyObj(__isl_keep Object *O) {
+  O->Ref++;
+  return O;
+}
+
+void freeObj(__isl_take Object *O) {
+  if (--O->Ref > 0)
+    return;
+
+  free(O); // Here we notice that the parameter contains '__isl_', escape it.
+}
+
+void useAfterFree(__isl_take Object *A) {
+  if (!A)
+    return;
+
+  Object *B = copyObj(A);
+  freeObj(B);
+
+  A->Ref = 13;
+  // no-warning: 'Use of memory after it is freed' was here.
+}