https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82619
Bug ID: 82619 Summary: C++17 std::apply treated as in global namespace under certain circumstances Product: gcc Version: 7.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: tower120 at gmail dot com Target Milestone: --- Created attachment 42403 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42403&action=edit cmake project. Look at test/main.cpp Under certain circumstances C++17's std::apply treated as if it is in global namespace. See attached cmake project. Specially src/reactive/oberver.h. Project is fail to compile, with function is ambiguous error. uncommenting /src/reactive/oberver.h line 49 makes it compilable.