PR fortran/95340 - ICE in gfc_match_select_rank, at fortran/match.c:6690

Do not dereference NULL pointer when querying array shape of possibly
improperly delared variable.

gcc/fortran/
	PR fortran/95340
	* match.c (gfc_match_select_rank): Do not dereference NULL pointer.

(cherry picked from commit b62cac6d92ff251213753475b69ec0b269cb7fae)

gcc/fortran/match.c

@@ -6695,7 +6695,8 @@ gfc_match_select_rank (void)
       if (expr1->symtree)
 	{
 	  sym = expr1->symtree->n.sym;
-	  as = sym->ts.type == BT_CLASS ? CLASS_DATA (sym)->as : sym->as;
+	  as = (sym->ts.type == BT_CLASS
+		&& CLASS_DATA (sym)) ? CLASS_DATA (sym)->as : sym->as;
 	}
 
       if (expr1->expr_type != EXPR_VARIABLE

gcc/testsuite/gfortran.dg/pr95340.f90

+! { dg-do compile }
+! PR fortran/95340 - ICE in gfc_match_select_rank, at fortran/match.c:6690
+
+program p
+  type t
+  end type t
+  class(t) :: z   ! { dg-error "must be dummy, allocatable or pointer" }
+  select rank (z) ! { dg-error "must be an assumed rank variable" }
+  end select      ! { dg-error "Expecting END PROGRAM" }
+end