When used with care the restrict type qualifier may improve the efficiency of code generated by a compiler. It may also allow improved static analysis. However, to use the restrict type qualifier the programmer must be sure that the memory areas operated on by two or more pointers do not overlap.

There is a significant risk that a compiler will generate code that does not behave as expected if restrict is used incorrectly.

Example

The following example is compliant because the MISRA C Guidelines do not apply to The Standard Library functions. The programmer must ensure that the areas defined by p, q and n do not overlap.

        #include <string.h>
void f ( void ) 
{
  /* memcpy has restrict-qualified parameters */ 
  memcpy ( p, q, n ); 
}

The following example is non-compliant because a function has been defined using restrict.

void user_copy ( void * restrict p, void * restrict q, size_t n ) 
{ 
}