target update to(mapper(m): x) and from(mapper(m): x) are rejected: "clause with modifier other than 'iterator' or 'present'"

// # Finding (GCC 16.2): the mapper modifier of the to and from clauses is rejected (C); the reproducer is the catalog program
//   omp52-c-clause-to-mapper
//
// - toolchains: gcc_g90 (GCC 16.2.0, AMD Instinct MI250X gfx90a, Tioga) and gcc_sm80 (GCC 16.2.0,
//   NVIDIA A100 sm_80, wingtip); separate memory only; -O2; OMP_TARGET_OFFLOAD=mandatory
// - build: gcc -fopenmp -foffload=amdgcn-amdhsa -foffload-options=amdgcn-amdhsa=-march=gfx90a -O2 (gcc_g90); -foffload=nvptx-none
//   -foffload-options=nvptx-none=-march=sm_80 -foffload-options=nvptx-none=-latomic -O2 (gcc_sm80)
// - failure: rejected: clause with modifier other than .iterator. or .present.
// - observed: `error: 'to' clause with modifier other than 'iterator' or 'present'` (and the same for from), on both GPUs. The
//   declare mapper directive and map(mapper(mm), tofrom: s) of the C map programs compile and pass at 5.0 and 5.2.
// - expected: compiles; `RESULT ran_on_host=0 check=pass`
// - GCC 16.2 documentation (libgomp.texi of the GCC 16.2.0 release tarball, "OpenMP Implementation Status", OpenMP 5.0 table):
//   "declare mapper directive": P, "Initial support and for C/C++, only"; no row names the motion clauses' mapper modifier.
// - spec: "mapper" is a modifier of the to clause (5.2 §5.9.1 p.166).
// - other families: AFAR and CCE 19/20/21 compile and run the program correctly (MI300A, both modes; MI250X); NVHPC rejects it.
// - gate and confirmer: 12 cells (6 gcc_g90, 6 gcc_sm80), each confirmed in the gate's four environments (a-d;
//   results/gcc/gate-tioga/ and gate-wingtip/ verdicts.jsonl); confirmer verdicts (results/gcc/confirm/batch.gcc_*.jsonl):
//   compiler_bug (R11-compile-rejection) 8, unsupported (R11a-newer-form-unclaimed) 4
// - catalog programs (6): omp50-c-clause-from-mapper, omp50-c-clause-to-mapper, omp52-c-clause-from-mapper,
//   omp52-c-clause-to-mapper, omp60-c-clause-from-mapper, omp60-c-clause-to-mapper
// - legality: the catalog programs are legal by construction (offload.engine.gen, c_gen and acc_gen
//   check every program against the catalog rules and the offload scope as it is built; no
//   compiler). GCC is a compiler under test only: never a legality witness, here or for another
//   family's case (catalog/machines.yaml under_test_only).
// Generated by compliance.c_gen (OpenMP 5.2, C11): the C port (offload.engine.f2c) of omp52-clause-to-mapper. Do not edit.
// id: omp52-c-clause-to-mapper
// primary atom: omp.clause.to.mapper
// legal: yes
// observable: yes
// ran_on_host: inside the target region of interest
// evidence: copy_mode_only
// needs: none
// std: c11
#include <stdio.h>
#include <stdbool.h>
#include <omp.h>

enum { n = 64 };
struct dt {
  int v[8];
  int w[8];
};
#pragma omp declare mapper(mm: struct dt q) map(q.v)

int main(void) {
  int a[n];
  int b[n];
  int ref[n];
  int host_flag;
  bool ok;
  struct dt s;
  int rv;
  int rw;
  bool pres;
  bool shared_mem;
  int zc[1];
  for (int i = 1; i <= n; i++) {
    a[i - 1] = i;
    b[i - 1] = 0;
    ref[i - 1] = 2 * i + 1;
  }
  host_flag = 1;
  for (int k1_ = 0; k1_ < 8; k1_++)
    s.v[k1_] = 1;
  for (int k2_ = 0; k2_ < 8; k2_++)
    s.w[k2_] = 1;
  rv = 0;
  rw = 0;
  pres = true;
  for (int k3_ = 0; k3_ < 1; k3_++)
    zc[k3_] = 0;
  #pragma omp target map(to: zc)
  {
    zc[0] = 1;
  }
  shared_mem = zc[0] == 1;
  #pragma omp target map(to: a) map(from: b) map(tofrom: host_flag)
  {
    host_flag = (omp_is_initial_device() ? 1 : 0);
    for (int i = 1; i <= n; i++) {
      b[i - 1] = 2 * a[i - 1] + 1;
    }
  }
  #pragma omp target enter data map(to: s)
  for (int k4_ = 0; k4_ < 8; k4_++)
    s.v[k4_] = 5;
  for (int k5_ = 0; k5_ < 8; k5_++)
    s.w[k5_] = 5;
  #pragma omp target update to(mapper(mm): s)
  #pragma omp target map(from: rv, rw)
  {
    rv = s.v[0];
    rw = s.w[0];
  }
  #pragma omp target exit data map(delete: s)
  if (!shared_mem) pres = pres && ((rv == 5) && (rw == 1));
  bool t6_ = true;
  for (int k7_ = 0; k7_ < n; k7_++)
    t6_ = t6_ && (b[k7_] == ref[k7_]);
  ok = t6_ && pres;
  printf("RESULT ran_on_host=%d check=%s\n", host_flag, ok ? "pass" : "fail");
  return 0;
}