More evidence that memory safety is the future for programming languages

[Walter Bright]

Some experimenting with clang shows it loses track of things when one level of 
indirection is added:

   struct S* malloc();
   void free(struct S*);

   void nut(struct S* s, int* pi) { free(s); *pi = 4; }

   void bolt()
   {
     struct S* s = malloc();
     struct S** ps = &s;     // <= add indirection
     nut(*ps, (*ps)->i);
   }

or when extern functions are used (i.e. function bodies are not available).

Other things clang doesn't detect:

   int* malloc();
   void free(int*);

   int nut();

   void bolt(int i)
   {
     int* p = malloc();
     *p = 1;
   }

Doesn't find the memory leak. Also, if you write your own storage allocator, 
clang doesn't pick it up.

clang actually does a nice job with what it has to work with - it's the C and 
C++ languages that are not amenable to doing it 100%.