[Bug c++/71662] New: ICE on invalid C++11 code with unqualified name look up: in tsubst_copy, at cp/pt.c:14010

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71662

            Bug ID: 71662
           Summary: ICE on invalid C++11 code with unqualified name look
                    up: in tsubst_copy, at cp/pt.c:14010
           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: ---

The following C++11 code causes an ICE when compiled with the current GCC trunk
on x86_64-linux-gnu in both 32-bit and 64-bit modes.  

It also affects older versions at least as early as 4.6.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 20160625 (experimental) [trunk revision 237780] (GCC) 
$ 
$ g++-trunk -c -std=c++11 small.cpp
small.cpp: In instantiation of ‘A<T>::E A<T>::h() [with T = int]’:
small.cpp:8:23:   required from here
small.cpp:14:10: internal compiler error: in tsubst_copy, at cp/pt.c:14010
   return e;
          ^
0x6dfcdc tsubst_copy
        ../../gcc-source-trunk/gcc/cp/pt.c:14010
0x6e2906 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:17243
0x6d68ff tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:15868
0x6d6f75 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:15176
0x6d7e30 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:15351
0x6d4835 instantiate_decl(tree_node*, int, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:22095
0x721512 instantiate_pending_templates(int)
        ../../gcc-source-trunk/gcc/cp/pt.c:22214
0x764645 c_parse_final_cleanups()
        ../../gcc-source-trunk/gcc/cp/decl2.c:4600
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$ 


----------------------------------------------------------


template < typename T > struct A
{
  enum E : T;
  E h ();
};

A < int > a;
A < int >::E b = a.h ();

template < typename T > enum A < T >::E : T { e };

template < typename T > typename A < T >::E A < T >::h ()
{
  return e; 
}