[Bug middle-end/103642] New: [12 Regression] ICE in lower_omp_target: omp-low.c:12977 (fold_convert_loc) for omp target map(from: t.s->a[:N])

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103642

            Bug ID: 103642
           Summary: [12 Regression] ICE in lower_omp_target:
                    omp-low.c:12977 (fold_convert_loc) for omp target
                    map(from: t.s->a[:N])
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code, openmp
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: cltang at gcc dot gnu.org, jakub at gcc dot gnu.org
  Target Milestone: ---

Compiling
https://github.com/clang-ykt/omptests/blob/master/t-partial-struct/test.cpp
fails now as follows:

during GIMPLE pass: omplower
t-partial-struct/test.cpp: In function ‘int main()’:
t-partial-struct/test.cpp:232:13: internal compiler error: in fold_convert_loc,
at fold-const.c:2450
  232 |     #pragma omp target map(from: t.s->a[:N])
      |             ^~~
0x7d313f fold_convert_loc(unsigned int, tree_node*, tree_node*)
        ../../repos/gcc/gcc/fold-const.c:2450
0x11218d4 lower_omp_target
        ../../repos/gcc/gcc/omp-low.c:12977
0x11218d4 lower_omp_1
        ../../repos/gcc/gcc/omp-low.c:14223
0x11218d4 lower_omp
        ../../repos/gcc/gcc/omp-low.c:14362


Until recently, it failed with:
  t-partial-struct/test.cpp:232:37: error: expected ')' before '->' token
which means this is a regression.


Reduced testcase - compile with "gcc / g++ -fopenmp":

typedef struct {
  int *a;
} SSS;
typedef struct {
  SSS *s;
} TTT;
main() {
  TTT t;
#pragma omp target map(t.s->a[9])
  ;
}