gcov: cannot open graph file

I used the following on Mac 10.8.4:

• Installed via xcode the command line tools:

• wrote this example code from the gcc website:

  #include <stdio.h>  
  main() 
  {  
     int i, total; total = 0; 
     for (i = 0; i < 10; i++) 
        total += i; 
     if (total != 45) 
        printf ("Failure\n"); 
     else 
        printf ("Success\n"); 
  }
  

• Compiling using the real GCC gcc-mp-4.7 -fprofile-arcs -ftest-coverage tmp.c

• And using GCC's gcov: gcov-mp-4.7 -b tmp.c will give you this output:

  File 'tmp.c'
  Lines executed:87.50% of 8
  Branches executed:100.00% of 4
  Taken at least once:75.00% of 4
  Calls executed:50.00% of 2
  Creating 'tmp.c.gcov'