https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72763
Bug ID: 72763 Summary: incorrectly accepts invalid C++11 code that instantiates a non-template class Product: gcc Version: 7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu Target Milestone: --- It affects 4.8.x and later, and is correctly rejected by 4.7.x. $ g++-trunk -v Using built-in specs. COLLECT_GCC=g++-trunk COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto --prefix=/usr/local/gcc-trunk --disable-bootstrap Thread model: posix gcc version 7.0.0 20160731 (experimental) [trunk revision 238915] (GCC) $ $ g++-trunk -c -Wall -Wextra -std=c++11 small.cpp $ clang++-3.8 -c -std=c++11 small.cpp small.cpp:3:25: error: 'D' following the 'template' keyword does not refer to a template template < typename T > using C = typename A < T >::template D < T >; ^~~~~ small.cpp:7:14: note: in instantiation of template type alias 'C' requested here struct D : C < T > {}; ^ 1 error generated. $ $ g++-4.7 -c -std=c++11 small.cpp small.cpp:3:69: error: ‘typename A< <template-parameter-1-1> >::D’ names ‘struct A< <template-parameter-1-1> >::D’, which is not a class template $ ----------------------------------------------------------------------- template < typename > struct A; template < typename T > using C = typename A < T >::template D < T >; template < typename T > struct A { struct D : C < T > {}; }; A < int > a;