http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56677
Bug #: 56677
Summary: [ratio] : ratio_multiply, ratio_divide, etc results
doesnt verify as __is_ratio
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: n...@chello.at
within chrono there is a test for template parameters if they classify as
ratios: __is_ratio
this test only works if the type is constructed as ratio<>, but the arithmetic
functions on ratio ratio_multiply, ratio_divide, .. dont generate the result
this way.
Here is a little programm to illustrate the issue:
------------------------------------------------------------------
#include <ratio>
#include <chrono>
typedef std::ratio_divide<std::ratio<1>, std::ratio<1> > ratii1;
typedef std::ratio<ratii1::num,ratii1::den > ratii2;
std::chrono::duration<unsigned long, ratii1 > d1; // compile time check raises
error
std::chrono::duration<unsigned long, ratii2 > d2; // works fine.
------------------------------------------------------------------
the solution would be either to make the __is_ratio smarter or, just generate
results like I did with ratii2.
