https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79702
Bug ID: 79702 Summary: AX_CXX_COMPILE_STDCXX([17]) does not work with GCC=7.0.1 Product: gcc Version: 7.0.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: kreckel at ginac dot de Target Milestone: --- This program is reduced from the C++17 conftest produced by the macro from https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html: #include <utility> struct S { int x1 : 2; volatile double y1; }; S f3() { return {}; } const auto [ x3, y3 ] = f3(); It fails to compile with g++ 7.0.1 20170205 on x86_64-pc-linux-gnu: $ g++ -std=c++17 -c conftest.cpp conftest.cpp:14:12: error: 'std::tuple_size<const S>::value' is not an integral constant expression const auto [ x3, y3 ] = f3(); ^~~~~~~~~~ The error has something to do with <utility>, as it goes away if I comment out the #include directive.