I would guess that std::static_assert(!(std::is_pointer<Src>::value && std::is_pointer<Dst>::value), "bit casting pointers doesn't solve the strict aliasing issue"); gives a better error message than linking error.
Vyacheslav Egorov On Wed, Dec 9, 2015 at 11:04 AM, Benedikt Meurer <bmeu...@chromium.org> wrote: > How about adding overloads for the template with pointers w/o > implementation? > > On Wed, Dec 9, 2015 at 10:59 AM, 'Erik Corry' via v8-dev < > v8-dev@googlegroups.com> wrote: > >> Yes. We plan to put in asserts to prevent it being used for pointer >> types. >> >> On 4 December 2015 at 15:30, Jochen Eisinger <joc...@chromium.org> wrote: >> >>> thanks for the heads-up. >>> >>> Did you keep the bit_casts in fletch for non-pointer types? >>> >>> On Thu, Dec 3, 2015 at 2:34 PM 'Erik Corry' via v8-dev < >>> v8-dev@googlegroups.com> wrote: >>> >>>> Slava points out that I am writing about use of bit_cast for pointer >>>> types (eg casting an Object** to a Class**), but ignoring the other use of >>>> bit_cast (eg casting a float to a uint32_t). It's only the pointer types >>>> that are problematic, I think. >>>> >>>> On 3 December 2015 at 13:37, Erik Corry <erikco...@google.com> wrote: >>>> >>>>> Some investigation by ager and some asking around has resulted in the >>>>> conclusion that bit_cast only serves to prevent warnings. It doesn't >>>>> actually fix the program's use of undefined behaviour. Mads was able to >>>>> get gcc to generate broken code for a function with strict aliasing issues >>>>> both with and without bit_cast. >>>>> >>>>> We have ripped bit_cast out of Fletch, replacing it with >>>>> reinterpret_cast everywhere. >>>>> >>>>> We have also added the -fno-strict-aliasing, since there's no sensible >>>>> way to fix a GC and a runtime for a dynamic language so it doesn't alias >>>>> pointers. (The only way I can think of involves getting rid of the C++ >>>>> "Object" class and treating the heap as a char array, which would be >>>>> horrible beyond belief). This flag is available on both Clang and gcc, >>>>> and >>>>> is the default behaviour for MSVC. If you add the same flag to V8 you may >>>>> see a small performance regression on Linux, but not on Mac and Windows >>>>> where I think it already is the default. >>>>> >>>>> -- >>>>> Erik Corry >>>>> >>>>> Google Denmark ApS >>>>> Frederiksborggade 20B, 1 sal >>>>> 1360 København K >>>>> Denmark >>>>> CVR nr. 28 86 69 84 >>>>> >>>> >>>> >>>> >>>> -- >>>> Erik Corry >>>> >>>> Google Denmark ApS >>>> Frederiksborggade 20B, 1 sal >>>> 1360 København K >>>> Denmark >>>> CVR nr. 28 86 69 84 >>>> >>>> -- >>>> -- >>>> v8-dev mailing list >>>> v8-dev@googlegroups.com >>>> http://groups.google.com/group/v8-dev >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "v8-dev" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to v8-dev+unsubscr...@googlegroups.com. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> -- >>> -- >>> v8-dev mailing list >>> v8-dev@googlegroups.com >>> http://groups.google.com/group/v8-dev >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "v8-dev" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to v8-dev+unsubscr...@googlegroups.com. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> Erik Corry >> >> Google Denmark ApS >> Frederiksborggade 20B, 1 sal >> 1360 København K >> Denmark >> CVR nr. 28 86 69 84 >> >> -- >> -- >> v8-dev mailing list >> v8-dev@googlegroups.com >> http://groups.google.com/group/v8-dev >> --- >> You received this message because you are subscribed to the Google Groups >> "v8-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to v8-dev+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > > -- > -- > v8-dev mailing list > v8-dev@googlegroups.com > http://groups.google.com/group/v8-dev > --- > You received this message because you are subscribed to the Google Groups > "v8-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to v8-dev+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- -- v8-dev mailing list v8-dev@googlegroups.com http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-dev+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
