Improve the failure message upon opt_experimental_infallible_new.

src/jemalloc_cpp.cpp

@@ -57,8 +57,14 @@ JEMALLOC_NOINLINE
 static void *
 handleOOM(std::size_t size, bool nothrow) {
 	if (opt_experimental_infallible_new) {
-		safety_check_fail("<jemalloc>: Allocation failed and "
-		    "opt.experimental_infallible_new is true. Aborting.\n");
+		const char *huge_warning = (size >= ((std::size_t)1 << 30)) ?
+		    "This may be caused by heap corruption, if the large size "
+		    "is unexpected (suggest building with sanitizers for "
+		    "debugging)." : "";
+
+		safety_check_fail("<jemalloc>: Allocation of size %zu failed. "
+		    "%s opt.experimental_infallible_new is true. Aborting.\n",
+		    size, huge_warning);
 		return nullptr;
 	}