On 04/26/2015 04:24 PM, Jonathan Wakely wrote:
On 26 April 2015 at 11:05, Avi Kivity wrote:@@ -526,12 +527,14 @@ public: } template <typename Func> - futurize_t<std::result_of_t<Func(T&&...)>> then(Func&& func) noexcept { + auto // futurize_t<std::result_of_t<Func(T&&...)>> + then(Func&& func) noexcept { returnThis changes the meaning of the code. For the original the function will not participate in overload resolution when result_of_t<Func(T&&...)> is not a valid type. You have changed that so the function can be called with invalid types and might be chosen by overload resolution, resulting in a compiler error. So feel free to do that in your own code if you want to avoid the compile-time overhead of SFINAE, but there are very good reasons it shouldn't be done in general.
What I don't understand is why the return type is passed to the linker. When the compiler is done with the translation unit, either there was exactly one overload that survived the compiler's overload resolution torture test, or there is no object file at all.
IOW, it is impossible (within ODR) for the linker to see two functions that only differ in return types. So why is the return type encoded in the mangled function name, given that it is so detrimental to compile times?
I realize this is an Itanium ABI question, not a gcc question, but I don't know of a forum where I can ask questions on the ABI. And as for the second question, are there plans to alleviate the pain somehow?
