map<int,int> x; x[0]; // no valgrind warning?

[xorbe]

I tried this code snippet + several variations, plus
using gcc 3.3 through 4.2, plus -00 through -03,
and Valgrind just does not throw up an uninitialized
variable warning:

  #include <stdio.h>
  #include <map>
  int main() {
    std::map<int,int> x;
    printf("%d\n", x[0]);
  }

I even pulled it up in gdb debugger, and nothing
writes to the memory location. I even added
x[0] = 1; at the end to verify the breakpoint worked.
updated: I made a second try and trapped the STL
writing 0 -- guess I botched the first attempt.

Yet, any such access WILL be zero initially! I'm
trying to prove that it will break to a co-worker -- but
I'm not winning so far.

What's going on? I don't see anything in the STL yet
that would guarantee such behavior for POD! Thanks,
Jason