http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58815
--- Comment #5 from Janis Johnson <janis at gcc dot gnu.org> --- >From Janis in http://gcc.gnu.org/ml/libstdc++/2009-09/msg00115.html The TR defines, within each of the classes decimal32, decimal64, and decimal128, the following conversion: // 3.2.[234].4 conversion to integral type: operator long long() const; Apparently there's a way to implement this if one knows enough about C++, but providing this implicit conversion from a decimal float type to long long allows further implicit conversions from long long to other types, including float, double, and long double, which are not supposed to be allowed. Furthermore, a conversion from a decimal float type to a generic float type that goes through long long truncates the fractional part of the value which is rather surprising. This version of the patch leaves out that conversion and provides a set of functions to convert to long long, which made testing the rest of the functionality much easier. Any suggestions for how to do with using the current (not C++0x) standard? Or is it OK to require the use of C++0x functionality with this extension? >From Benjamin Kosnik in http://gcc.gnu.org/ml/libstdc++/2009-09/msg00127.html I think it is not ok to require the use of C++0x with the decimal floating point extension. It is clearly designed with C++2003 in mind, and makes no use of C++0x features. When you post testsuite files demonstrating this issue in detail I'll take a look at this overload issue. >From Janis in http://gcc.gnu.org/ml/libstdc++/2009-10/msg00004.html With the submission on Monday I mentioned that this patch does not support an implicit conversion to integral types (long long) from each of the decimal classes. Those are in the patch, commented out and with a comment that now says (DISABLED). If those are not disabled then all of the error checks in the bad-*.cc tests fail. I can't see how to allow implicit conversions to long long while also prohibiting bitwise operations with decimal floating-point operands or conversions and casts to generic floating-point types. I didn't find any further discussion of this issue.
