CMake/Source/cmDuration.cxx
Wouter Klouwen ff62b00522 CTest: add safe conversion from cmDuration to integer types
A problem area by recent refactoring of time to std::chrono has been the
unsafe conversion from duration<double> to std::chrono::seconds, which
is of an unspecified integer type.

This commit adds a template function that for a given type provides a
safe conversion, effectively clamping a duration<double> into what fits
safely in that type. A specialisation for int and unsigned int are
provided.

It changes the protential problem areas to use this safe function.
2018-01-23 10:05:12 -05:00

28 lines
985 B
C++

/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
file Copyright.txt or https://cmake.org/licensing for details. */
#define CMDURATION_CPP
#include "cmDuration.h"
template <typename T>
T cmDurationTo(const cmDuration& duration)
{
/* This works because the comparison operators for duration rely on
* std::common_type.
* So for example duration<int>::max() gets promoted to a duration<double>,
* which can then be safely compared.
*/
if (duration >= std::chrono::duration<T>::max()) {
return std::chrono::duration<T>::max().count();
}
if (duration <= std::chrono::duration<T>::min()) {
return std::chrono::duration<T>::min().count();
}
// Ensure number of seconds by defining ratio<1>
return std::chrono::duration_cast<std::chrono::duration<T, std::ratio<1>>>(
duration)
.count();
}
template int cmDurationTo<int>(const cmDuration&);
template unsigned int cmDurationTo<unsigned int>(const cmDuration&);