$ uname -a
NetBSD chieftec 8.99.8 NetBSD 8.99.8 (GENERIC) #1: Thu Dec  7 02:50:00 CET 2017  root@chieftec:/public/netbsd-root/sys/arch/amd64/compile/GENERIC amd64
$ cat umr.cpp
#include <stdio.h>

int main(int argc, char** argv) {
  int a[10];
  a[5] = 0;
  if (a[argc])
    printf("xx\n");
  return 0;
}
$ ./bin/clang++ -fsanitize=memory -g -O0 umr.cpp
$ ./a.out
==846==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x44e83c in main /public/llvm-build/umr.cpp:6:7
    #1 0x40ae3a in ___start (/public/llvm-build/./a.out+0x40ae3a)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /public/llvm-build/umr.cpp:6:7 in main
Exiting

---------------------------------------------------------------------

$ uname -a
Linux a.b 4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26) x86_64 GNU/Linux
$ clang++ -fsanitize=memory -g -O0 umr.cpp
$ ./a.out
==2147==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x48ba24 in main /home/kamil/umr.cpp:6:7
    #1 0x7fb36b9832b0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202b0)
    #2 0x41c399 in _start (/home/kamil/a.out+0x41c399)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /home/kamil/umr.cpp:6:7 in main
Exiting