integer division by zero isn't caught

[bob-carpenter]

Summary:

Integer divide by zero throws an uncaught exception.

Description:

Running this crashes RStan:

library(rstan)

mc <- '
parameters {real theta;}
model {
  target += 1/0;
}
'
sm <- stan_model(model_code = mc)
post <- sampling(sm, show_messages = FALSE)

I'm reporting in Stan because in the command refactor, we'll be catching this in Stan itself.

Reproducible Steps:

See above.

Current Output:

Crashes with `Floating point exception: 8

Expected Output:

Informative error message.

Additional Information:

Originally reported by @davharris on RStan tracker in issue stan-dev/rstan#316

Current Version:

v2.10.0

[syclik]

The problem is in math:
https://github.com/stan-dev/math/blob/develop/stan/math/prim/scal/fun/divide.hpp#L25

This line has undefined behavior:

return std::div(x, y).quot;

I didn't realize it threw an exception outside of the stdexcept types. Any suggestions on how to fix this call?

[bob-carpenter]

Overload for int and check for zero in denominator?

Do you know what it does throw? If so, you could catch
and rethrow.

• Bob

On Jul 25, 2016, at 5:43 PM, Daniel Lee notifications@github.com wrote:

The problem is in math:
https://github.com/stan-dev/math/blob/develop/stan/math/prim/scal/fun/divide.hpp#L25

This line has undefined behavior:

return std::div(x, y).quot;

I didn't realize it threw an exception outside of the stdexcept types. Any suggestions on how to fix this call?

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[syclik]

The internet is saying check for 0, so that's the fix I'll apply.

On Jul 25, 2016, at 5:57 PM, Bob Carpenter notifications@github.com wrote:

Overload for int and check for zero in denominator?

Do you know what it does throw? If so, you could catch
and rethrow.

• Bob

On Jul 25, 2016, at 5:43 PM, Daniel Lee notifications@github.com wrote:

The problem is in math:
https://github.com/stan-dev/math/blob/develop/stan/math/prim/scal/fun/divide.hpp#L25

This line has undefined behavior:

return std::div(x, y).quot;

I didn't realize it threw an exception outside of the stdexcept types. Any suggestions on how to fix this call?

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You are receiving this because you authored the thread.
Reply to this email directly, view it on GitHub, or mute the thread.

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[syclik]

This issue was moved to stan-dev/math#321