[Bug c++/71820] New: ICE on valid C++ code: in arg_assoc_type, at cp/name-lookup.c:5583

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71820

            Bug ID: 71820
           Summary: ICE on valid C++ code: in arg_assoc_type, at
                    cp/name-lookup.c:5583
           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++ 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 appears to affect all versions since at least as early as 4.4.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 20160707 (experimental) [trunk revision 238117] (GCC)
$
$ clang++-3.8 -c small.cpp
$
$ g++-trunk -c small.cpp
small.cpp: In substitution of ‘template<class T> void f1(__typeof__ (f(f0<T>)))
[with T = int]’:
small.cpp:13:16:   required from here
small.cpp:8:24: internal compiler error: in arg_assoc_type, at
cp/name-lookup.c:5583
 void f1 (__typeof__ (f (f0 < T >))) {}
                     ~~~^~~~~~~~~~~
0x8778d2 arg_assoc_type
        ../../gcc-source-trunk/gcc/cp/name-lookup.c:5583
0x877866 arg_assoc_args
        ../../gcc-source-trunk/gcc/cp/name-lookup.c:5594
0x877866 arg_assoc_type
        ../../gcc-source-trunk/gcc/cp/name-lookup.c:5566
0x8770cd arg_assoc
        ../../gcc-source-trunk/gcc/cp/name-lookup.c:5665
0x877298 arg_assoc
        ../../gcc-source-trunk/gcc/cp/name-lookup.c:5653
0x87c6d1 arg_assoc_args_vec
        ../../gcc-source-trunk/gcc/cp/name-lookup.c:5609
0x87c6d1 lookup_arg_dependent_1
        ../../gcc-source-trunk/gcc/cp/name-lookup.c:5714
0x87c6d1 lookup_arg_dependent(tree_node*, tree_node*, vec<tree_node*, va_gc,
vl_embed>*)
        ../../gcc-source-trunk/gcc/cp/name-lookup.c:5742
0x815644 perform_koenig_lookup(cp_expr, vec<tree_node*, va_gc, vl_embed>*, int)
        ../../gcc-source-trunk/gcc/cp/semantics.c:2244
0x6e542e tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:16590
0x6d6c2f tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:15868
0x6ea34a tsubst(tree_node*, tree_node*, int, tree_node*)
        ../../gcc-source-trunk/gcc/cp/pt.c:13569
0x6f8752 tsubst_arg_types
        ../../gcc-source-trunk/gcc/cp/pt.c:12559
0x6f8b4c tsubst_function_type
        ../../gcc-source-trunk/gcc/cp/pt.c:12694
0x6e9fb7 tsubst(tree_node*, tree_node*, int, tree_node*)
        ../../gcc-source-trunk/gcc/cp/pt.c:13416
0x713b1d 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:17795
0x67468b add_template_candidate_real
        ../../gcc-source-trunk/gcc/cp/call.c:3110
0x6753bc add_template_candidate
        ../../gcc-source-trunk/gcc/cp/call.c:3188
0x6753bc add_candidates
        ../../gcc-source-trunk/gcc/cp/call.c:5361
0x6779b9 perform_overload_resolution
        ../../gcc-source-trunk/gcc/cp/call.c:4045
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.
$


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


int f (int);
int f (void (*) (int, int));

template < typename T >
void f0 (T x, __typeof__ (f (x)) y) {}

template < typename T >
void f1 (__typeof__ (f (f0 < T >))) {}

int main ()
{ 
  f0 < int > (0, 0);
  f1 < int > (0);
  return 0;
}