https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81259
Bug ID: 81259 Summary: Class template deduction cannot work on Constructor without parameters in some cases Product: gcc Version: 7.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: kmp53 at sina dot com CC: webrown.cpp at gmail dot com Target Milestone: --- CC: webrown.cpp at gmail dot com template<int N=128> class C { public: void fn(){} }; int main(int argc,char*argv[]){ C c;//OK C{}.fn();//OK C().fn();//cannot deduce template arguments for 'C' from () }