[Bug c++/71451] New: ICE on invalid C++11 code on x86_64-linux-gnu: in dependent_type_p, at cp/pt.c:22599

["su at cs dot ucdavis.edu" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71451

            Bug ID: 71451
           Summary: ICE on invalid C++11 code on x86_64-linux-gnu: in
                    dependent_type_p, at cp/pt.c:22599
           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 code causes an ICE when compiled with the current gcc trunk on
x86_64-linux-gnu in both 32-bit and 64-bit modes.

This is a regression from 4.7.x (as it seems to affect 4.8.x and later). 


$ 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 20160607 (experimental) [trunk revision 237165] (GCC)
$
$ g++-trunk -std=c++11 small.cpp
small.cpp:6:39: error: parameter packs not expanded with â...â:
   template < typename A < T::value >::type > void foo ();
                                       ^~~~
small.cpp:6:39: note:         âTâ
small.cpp: In substitution of âtemplate<typename A<T:: value>::type
...<anonymous> > void B<T>::foo() [with typename A<T:: value>::type
...<anonymous> = {}]â:
small.cpp:12:10:   required from here
small.cpp:6:51: internal compiler error: in dependent_type_p, at cp/pt.c:22599
   template < typename A < T::value >::type > void foo ();
                                                   ^~~
0x6c1b53 dependent_type_p(tree_node*)
        ../../gcc-source-trunk/gcc/cp/pt.c:22599
0x6c2380 dependent_scope_p(tree_node*)
        ../../gcc-source-trunk/gcc/cp/pt.c:22630
0x6de2e4 tsubst_qualified_id
        ../../gcc-source-trunk/gcc/cp/pt.c:13753
0x6df3d4 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:16224
0x6d401f tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:15820
0x6ea07c tsubst_template_arg
        ../../gcc-source-trunk/gcc/cp/pt.c:10391
0x6f9482 tsubst_template_args
        ../../gcc-source-trunk/gcc/cp/pt.c:11234
0x6fe28b tsubst_aggr_type
        ../../gcc-source-trunk/gcc/cp/pt.c:11431
0x6e7121 tsubst(tree_node*, tree_node*, int, tree_node*)
        ../../gcc-source-trunk/gcc/cp/pt.c:13432
0x6f95de tsubst_template_args
        ../../gcc-source-trunk/gcc/cp/pt.c:11226
0x6f96fa tsubst_template_args
        ../../gcc-source-trunk/gcc/cp/pt.c:11194
0x6eff05 tsubst_decl
        ../../gcc-source-trunk/gcc/cp/pt.c:11726
0x6e799e tsubst(tree_node*, tree_node*, int, tree_node*)
        ../../gcc-source-trunk/gcc/cp/pt.c:12829
0x6ffbcd instantiate_template_1
        ../../gcc-source-trunk/gcc/cp/pt.c:17421
0x6ffbcd instantiate_template(tree_node*, tree_node*, int)
        ../../gcc-source-trunk/gcc/cp/pt.c:17472
0x71161c fn_type_unification(tree_node*, tree_node*, tree_node*, tree_node*
const*, unsigned int, tree_node*, unification_kind_t, int, bool, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:17847
0x67243b add_template_candidate_real
        ../../gcc-source-trunk/gcc/cp/call.c:3110
0x67316c add_template_candidate
        ../../gcc-source-trunk/gcc/cp/call.c:3188
0x67316c add_candidates
        ../../gcc-source-trunk/gcc/cp/call.c:5361
0x673a06 build_new_method_call_1
        ../../gcc-source-trunk/gcc/cp/call.c:8313
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 < int > struct A;

template < typename ... T >
struct B
{ 
  template < typename A < T::value >::type > void foo ();
};

int main ()
{ 
  B < int > t;
  t.foo ();
  return 0;
}