[Bug c++/70344] New: ICE on valid code at -O1 and above on x86_64-linux-gnu in adjust_temp_type, at cp/constexpr.c:1078

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70344

            Bug ID: 70344
           Summary: ICE on valid code at -O1 and above on x86_64-linux-gnu
                    in adjust_temp_type, at cp/constexpr.c:1078
           Product: gcc
           Version: 6.0
            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 at -O1 and above in both 32-bit and 64-bit modes. 

This is a regression from 5.3.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/6.0.0/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 6.0.0 20160321 (experimental) [trunk revision 234361] (GCC) 
$ 
$ g++-trunk -O0 -std=c++11 -c small.cpp
$ g++-5.3 -O1 -std=c++11 -c small.cpp
$ 
$ g++-trunk -O1 -std=c++11 -c small.cpp
small.cpp: In instantiation of âconstexpr int fn(T) [with T = Z]â:
small.cpp:15:18:   required from here
small.cpp:13:1: internal compiler error: in adjust_temp_type, at
cp/constexpr.c:1078
 }
 ^
0x84505a adjust_temp_type
        ../../gcc-source-trunk/gcc/cp/constexpr.c:1078
0x84bbfb cxx_bind_parameters_in_call
        ../../gcc-source-trunk/gcc/cp/constexpr.c:1128
0x84bbfb cxx_eval_call_expression
        ../../gcc-source-trunk/gcc/cp/constexpr.c:1312
0x84d57b cxx_eval_constant_expression
        ../../gcc-source-trunk/gcc/cp/constexpr.c:3381
0x853a19 cxx_eval_outermost_constant_expr
        ../../gcc-source-trunk/gcc/cp/constexpr.c:3946
0x85671c maybe_constant_value_1
        ../../gcc-source-trunk/gcc/cp/constexpr.c:4134
0x85671c maybe_constant_value(tree_node*, tree_node*)
        ../../gcc-source-trunk/gcc/cp/constexpr.c:4155
0x830a9f cp_fold
        ../../gcc-source-trunk/gcc/cp/cp-gimplify.c:2188
0x830816 cp_fold_rvalue
        ../../gcc-source-trunk/gcc/cp/cp-gimplify.c:1887
0x830816 cp_fold
        ../../gcc-source-trunk/gcc/cp/cp-gimplify.c:2072
0x83135e cp_fold_r
        ../../gcc-source-trunk/gcc/cp/cp-gimplify.c:944
0x1009b64 walk_tree_1(tree_node**, tree_node* (*)(tree_node**, int*, void*),
void*, hash_set<tree_node*, default_hash_traits<tree_node*> >*, tree_node*
(*)(tree_node**, int*, tree_node* (*)(tree_node**, int*, void*), void*,
hash_set<tree_node*, default_hash_traits<tree_node*> >*))
        ../../gcc-source-trunk/gcc/tree.c:11531
0x65701f finish_function(int)
        ../../gcc-source-trunk/gcc/cp/decl.c:14688
0x67b622 instantiate_decl(tree_node*, int, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:22029
0x7098ea mark_used(tree_node*, int)
        ../../gcc-source-trunk/gcc/cp/decl2.c:5279
0x612481 build_over_call
        ../../gcc-source-trunk/gcc/cp/call.c:7706
0x621b3f build_new_function_call(tree_node*, vec<tree_node*, va_gc,
vl_embed>**, bool, int)
        ../../gcc-source-trunk/gcc/cp/call.c:4152
0x7bc4a1 finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
        ../../gcc-source-trunk/gcc/cp/semantics.c:2461
0x736799 cp_parser_postfix_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:6904
0x73fb0c cp_parser_unary_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:7988
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.
$ 


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


struct Z
{
  Z () = default;
  Z (Z const &) = default;
  constexpr Z (Z &&) {}
};

template < typename T > 
constexpr int 
fn (T v)
{
  return fn (v);
}

auto t = fn (Z ());