[Bug middle-end/118157] New: [OpenMP] Variant function - build failed due to auto-tagged as 'declare target' but uncalled + not callable

[burnus at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118157

            Bug ID: 118157
           Summary: [OpenMP] Variant function - build failed due to
                    auto-tagged as 'declare target' but uncalled + not
                    callable
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: openmp, rejects-valid
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: sandra at gcc dot gnu.org
  Target Milestone: ---

The following code is rejected with:

var.c:1:5: error: variable 'x' has been referenced in offloaded code but hasn't
been marked to be included in the offbut uncalledloaded code
    1 | int x = 123;
      |     ^
lto1: fatal error: errors during merging of translation units


The problem is that 'f' is has:
  __attribute__((omp declare target, omp declare variant variant))

However, the condition   device={isa("avx512f")}  can never be true for
devices, but it still gets the 'declare target' attribute.

Note that during gimplify, it is already resolved to:

        #pragma omp target num_teams(-2) thread_limit(0) map(from:y [len: 4])
          {
            int y.0;

            y.0 = h ();
            y = y.0;
          }

Thus, there is no need for 'f' getting the 'declare target'.
*******************

int x = 123;

int f() {
  return (int) x;
}

int h() {
  return 12;
}

#pragma omp declare variant(f) match(device={isa("avx512f")})
#pragma omp declare variant (h) match (user={condition(score(20): 1)})

int foo() {
 return 3;
}

int main()
{
  int y;
  #pragma omp target map(from: y)
    y = foo();
  __builtin_printf("y = %d\n", y);
}