[Bug c++/86426] New: g++ ICE at on valid code in tree_operand_check, at tree.h:3615

[helloqirun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86426

            Bug ID: 86426
           Summary: g++ ICE at on valid code in tree_operand_check, at
                    tree.h:3615
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: helloqirun at gmail dot com
  Target Milestone: ---

It affects versions from 4.8 to trunk.
g++4.6 emits errors. But clang++ can compile.


$ g++-trunk -v
Using built-in specs.
COLLECT_GCC=g++-trunk
COLLECT_LTO_WRAPPER=/home/absozero/trunk/root-gcc/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/home/absozero/trunk/root-gcc
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 9.0.0 20180706 (experimental) [trunk revision 262476] (GCC)


$ g++-trunk abc.c
abc.c: In substitution of ‘template<class ... T> int {anonymous}::f1(X<T, T
...>...) [with T = <missing>]’:
abc.c:4:26:   required from here
abc.c:4:26: internal compiler error: tree check: expected class ‘expression’,
have ‘type’ (integer_type) in tree_operand_check, at tree.h:3615
 int a1 = f1(X<int, int>());
                          ^
0x78c90b tree_class_check_failed(tree_node const*, tree_code_class, char
const*, int, char const*)
        ../../gcc/gcc/tree.c:9403
0x651e95 expr_check(tree_node*, char const*, int, char const*)
        ../../gcc/gcc/tree.h:3286
0x651e95 tree_operand_check(tree_node*, int, char const*, int, char const*)
        ../../gcc/gcc/tree.h:3615
0x651e95 unify_pack_expansion
        ../../gcc/gcc/cp/pt.c:21125
0x97665d unify
        ../../gcc/gcc/cp/pt.c:21919
0x9758b3 unify
        ../../gcc/gcc/cp/pt.c:22116
0x976612 unify
        ../../gcc/gcc/cp/pt.c:21913
0x974e92 try_class_unification
        ../../gcc/gcc/cp/pt.c:20907
0x9766b5 unify
        ../../gcc/gcc/cp/pt.c:21950
0x97bb93 unify_one_argument
        ../../gcc/gcc/cp/pt.c:20161
0x97c914 unify_pack_expansion
        ../../gcc/gcc/cp/pt.c:21156
0x97dce3 type_unification_real
        ../../gcc/gcc/cp/pt.c:20300
0x97ee7f fn_type_unification(tree_node*, tree_node*, tree_node*, tree_node*
const*, unsigned int, tree_node*, unification_kind_t, int, conversion**, bool,
bool)
        ../../gcc/gcc/cp/pt.c:19660
0x826a02 add_template_candidate_real
        ../../gcc/gcc/cp/call.c:3212
0x827414 add_template_candidate
        ../../gcc/gcc/cp/call.c:3291
0x827414 add_candidates
        ../../gcc/gcc/cp/call.c:5532
0x827801 add_candidates
        ../../gcc/gcc/cp/call.c:4225
0x827801 perform_overload_resolution
        ../../gcc/gcc/cp/call.c:4233
0x829722 build_new_function_call(tree_node*, vec<tree_node*, va_gc,
vl_embed>**, int)
        ../../gcc/gcc/cp/call.c:4306
0x9a0dad finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
        ../../gcc/gcc/cp/semantics.c:2536
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.


$ cat abc.c
template <typename...> struct X {};
namespace {
template <typename... T> int f1(X<T, T...>...);
int a1 = f1(X<int, int>());
}