Re: C2124 is most disrespectful of IEEE floating point arithmetic

John Carson wrote:

"Dr Pizza" <DrPizza@xxxxxxxxxxxxxxxxx> wrote in message
news:xn0eqhw1a4lwx05000@xxxxxxxxxxxxxxxxxxxx
Since VC++ purports to follow IEC 559, and IEC 559 defines the
division of a non-zero by a zero to be a signed infinity, isn't it
rather silly that:

float inf(1.0f / 0.0f);

should result in a compile-time error, C2124? An error may be
appropriate for integer arithmetic (as it'll generate a runtime SEH
exception), but for floating point arithmetic it's surely incorrect
behaviour?

What gives? Am I being unreasonable in my expectations? It's
certainly rather nicer to type the above than have to spew:

float inf(std::numeric_limits<float>::infinity());


For what it is worth, this compiles:

float zero = 0.0f;
float f(1.0f/zero);

as does

const float zero = 0.0f;
float f(1.0f/zero);

It is apparently only a literal zero that gives a problem.

Weird. I had expected that the compiler would propagate the constant
zero and emit the same error, but looking at the generated assembly it
doesn't; it performs a runtime division.

--

.

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