[Bug c++/84791] New: ICE with broken OpenMP reduction clause

[reichelt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84791

            Bug ID: 84791
           Summary: ICE with broken OpenMP reduction clause
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: error-recovery, ice-on-invalid-code, openmp
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: reichelt at gcc dot gnu.org
  Target Milestone: ---

The following invalid code snippet (compiled with "-fopenmp") triggers an
ICE since GCC 4.9.0 (when OpenMP 4.0 was implemented):

==============================================
typedef int I;

template<int> void foo()
{
  I i;
  #pragma omp parallel reduction (I::I: i)
    ;
}

template void foo<0>();
==============================================

bug.cc: In function 'void foo()':
bug.cc:6:35: error: 'I' is not a class, namespace, or enumeration
   #pragma omp parallel reduction (I::I: i)
                                   ^
bug.cc: In instantiation of 'void foo() [with int <anonymous> = 0]':
bug.cc:10:22:   required from here
bug.cc:6:11: internal compiler error: in tsubst_omp_clauses, at cp/pt.c:15664
   #pragma omp parallel reduction (I::I: i)
           ^~~
0x643d33 tsubst_omp_clauses
        ../../gcc/gcc/cp/pt.c:15664
0x96d9ba tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc/gcc/cp/pt.c:16654
0x96d4e4 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc/gcc/cp/pt.c:16190
0x96aecf tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc/gcc/cp/pt.c:16471
0x96a168 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc/gcc/cp/pt.c:16175
0x96a168 instantiate_decl(tree_node*, bool, bool)
        ../../gcc/gcc/cp/pt.c:23540
0x98eb4b instantiate_pending_templates(int)
        ../../gcc/gcc/cp/pt.c:23656
0x8b632b c_parse_final_cleanups()
        ../../gcc/gcc/cp/decl2.c:4721
Please submit a full bug report, [etc.]