Division by complex in clang++ versus g++

Question

When I compile the following code with g++ (4.8.1 or 4.9.0) or clang++ (3.4) I get different outputs.

#include 
#include 

int mai         


        

Answer 1

The standard says in [complex.numbers] (26.4/3):

If the result of a function is not mathematically defined or not in the range of representable values for its type, the behavior is undefined.

There are no specifics on how division should be implemented for complex numbers. Only in [complex.member.ops] it says:

complex& operator/=(const complex& rhs);

Effects: Divides the complex value rhs into the complex value *this and stores the quotient in *this. Returns: *this.

and in [complex.ops]:

template complex operator/(const T& lhs, const complex& rhs);

Returns: complex(lhs) /= rhs.

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As the inverse of 1.e-162 is 1.e+162 and this number is in the range of representable values for a double, the behavior is well defined.

Thus gcc gets it right and clang has a bug.