[Bug c/14319] incorrect optimization of union of structs with common initial sequences

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-02-27 15:19 -------
I can't believe the wording means what you imply. Assume that caller 
and callee are in different translation units, then there is no 
way for the compiler to see that the two arguments to the called function 
may in fact be members of the same union. 
 
So the only way to assume that they could alias each other is to 
search the universe for a union type in which both of them are members. 
That certainly can't be the intent of the standard or DR. It only makes 
sense, if as RTH says the access is through such a union. 
 
W. 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14319