boost::chrono::floor()/round() and negative durations is wrong

[1czajnik@…]

The assert in the following program fails:

#include <boost/chrono/floor.hpp>
#include <cassert>

int main()
{
    boost::chrono::nanoseconds const nsec( -1 );
    boost::chrono::seconds const sec = 
        boost::chrono::floor<boost::chrono::seconds>(nsec);
    assert( sec.count() == -1 );
}

Regards, Kris

[1czajnik@…]

unit test demonstrating the problem

[1czajnik@…]

The attached unit test demonstrates the problem, as well as a problem with round<>, which I think doesn't follow the documented rule "tie towards even" for negative values.

There are also overflow tests, and they all pass ;-)

My output of this test is:

Running 4 test cases...
../chrono_rounding.cpp(28): error in "floor_": check seconds(-2) == floor<seconds>( milliseconds(-1999) ) failed [-2 seconds != -1 second]
../chrono_rounding.cpp(29): error in "floor_": check seconds(-2) == floor<seconds>( milliseconds(-1001) ) failed [-2 seconds != -1 second]
../chrono_rounding.cpp(31): error in "floor_": check seconds(-1) == floor<seconds>( milliseconds(-999) ) failed [-1 second != 0 seconds]
../chrono_rounding.cpp(32): error in "floor_": check seconds(-1) == floor<seconds>( milliseconds(-1) ) failed [-1 second != 0 seconds]
../chrono_rounding.cpp(63): error in "round_": check seconds(-2) == round<seconds>( milliseconds(-1500) ) failed [-2 seconds != -1 second]

*** 5 failures detected in test suite "Master Test Suite"

HTH, Kris

[viboes]

Replying to 1czajnik@…:

The attached unit test demonstrates the problem, as well as a problem with round<>, which I think doesn't follow the documented rule "tie towards even" for negative values.

There are also overflow tests, and they all pass ;-)

My output of this test is:

Running 4 test cases...
../chrono_rounding.cpp(28): error in "floor_": check seconds(-2) == floor<seconds>( milliseconds(-1999) ) failed [-2 seconds != -1 second]
../chrono_rounding.cpp(29): error in "floor_": check seconds(-2) == floor<seconds>( milliseconds(-1001) ) failed [-2 seconds != -1 second]
../chrono_rounding.cpp(31): error in "floor_": check seconds(-1) == floor<seconds>( milliseconds(-999) ) failed [-1 second != 0 seconds]
../chrono_rounding.cpp(32): error in "floor_": check seconds(-1) == floor<seconds>( milliseconds(-1) ) failed [-1 second != 0 seconds]
../chrono_rounding.cpp(63): error in "round_": check seconds(-2) == round<seconds>( milliseconds(-1500) ) failed [-2 seconds != -1 second]

*** 5 failures detected in test suite "Master Test Suite"

HTH, Kris

Thanks Kris for the report.

I would take care of it. Clearly we missed the negative numbers :(

Best, Vicente

[viboes]

Merged to master ​https://github.com/boostorg/chrono/commit/143260daeb2703961448a0928d199747ca34dfca