Useful flags for clang address sanitizer

From Loius Brandy’s CppCon 2017 talk.

Asan has a ‘use after scope’ option which is not enabled by default (until recently). Turn it on with -fsanitize-address-use-after-scope.

Catches bugs like this one:

volatile int *p = 0;

int main() {
  {
    int x = 0;
    p = &x;
  }
  *p = 5;
  return 0;
}