gcc, strict-aliasing, and casting through a union

Question

Do you have any horror stories to tell? The GCC Manual recently added a warning regarding -fstrict-aliasing and casting a pointer through a union:

[.

Answer 1

Have you seen this ? What is the strict aliasing rule?

The link contains a secondary link to this article with gcc examples. http://cellperformance.beyond3d.com/articles/2006/06/understanding-strict-aliasing.html

Trying a union like this would be closer to the problem.

union a_union {
    int i;
    double *d;
};

That way you have 2 types, an int and a double* pointing to the same memory. In this case using the double (*(double*)&i) could cause the problem.