tree-nested: Update assert for Fortran module vars [PR97927]

gcc/ChangeLog:

	PR fortran/97927
	* tree-nested.c (convert_local_reference_stmt): Avoid calling
	lookup_field_for_decl for Fortran module (= namespace context).

gcc/testsuite/ChangeLog:

	PR fortran/97927
	* gfortran.dg/module_variable_3.f90: New test.

gcc/testsuite/gfortran.dg/module_variable_3.f90

@@ -0,0 +1,37 @@
+! { dg-do compile }
+! { dg-additional-options "-fdump-tree-original" }
+!
+! PR fortran/97927
+!
+! Did ICE due to the in tree-nested.c due to {clobber}
+!
+
+module mpi2
+ interface
+   subroutine MPI_Allreduce(i)
+     implicit none
+     INTEGER, OPTIONAL, INTENT(OUT) :: i
+   end subroutine MPI_Allreduce
+ end interface
+end module
+
+module modmpi
+  implicit none
+  integer ierror  ! module variable = context NAMESPACE_DECL
+end module
+
+subroutine exxengy
+  use modmpi
+  use mpi2, only: mpi_allreduce
+  implicit none
+
+  ! intent(out) implies: ierror = {clobber}
+  call mpi_allreduce(ierror)
+
+contains
+  subroutine zrho2
+    return
+  end subroutine
+end subroutine
+
+! { dg-final { scan-tree-dump "ierror = {CLOBBER};" "original" } }

gcc/tree-nested.c

@@ -2526,6 +2526,7 @@ convert_local_reference_stmt (gimple_stmt_iterator *gsi, bool *handled_ops_p,
 	{
 	  tree lhs = gimple_assign_lhs (stmt);
 	  if (DECL_P (lhs)
+	      && decl_function_context (lhs) == info->context
 	      && !use_pointer_in_frame (lhs)
 	      && lookup_field_for_decl (info, lhs, NO_INSERT))
 	    {