gcc failing to give warnings

foo.c

#include <stdio.h>

void test()
{
  int iters;

  while(iters++ <= 100) {
    printf("%d\n", iters);
  }
  
}

int main() 
{
  test();
  return 0;
}

Runs

# With gcc
noufal@sanitarium% CFLAGS=-Wall make foo
cc -Wall    foo.c   -o foo


# With clang
noufal@sanitarium% CFLAGS=-Wall CC==clang make foo
/home/noufal/local/bin//clang -Wall    foo.c   -o foo
foo.c:7:9: warning: variable 'iters' is uninitialized when used here [-Wuninitialized]
  while(iters++ <= 100) {
        ^~~~~
foo.c:5:12: note: initialize the variable 'iters' to silence this warning
  int iters;
           ^
            = 0
1 warning generated.


# Using valgrind
noufal@sanitarium% valgrind ./foo
==15231== Memcheck, a memory error detector
==15231== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==15231== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==15231== Command: ./foo
==15231== 
==15231== Conditional jump or move depends on uninitialised value(s)
==15231==    at 0x40050B: test (in /tmp/foo)
==15231==    by 0x400553: main (in /tmp/foo)
==15231== 
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