re PR fortran/91359 (logical function X returns .TRUE. - Warning: spaghetti code)

2019-08-06  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/91359
	* trans-decl.c (gfc_generate_return): Ensure something is returned
	from a function.

2019-08-06  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/91359
	* gfortran.dg/pr91359_1.f: New test.
	* gfortran.dg/pr91359_2.f: Ditto.

From-SVN: r274149

gcc/fortran/ChangeLog

 2019-08-06  Steven G. Kargl  <kargl@gcc.gnu.org>
 
+	PR fortran/91359
+	* trans-decl.c (gfc_generate_return): Ensure something is returned
+	from a function.
+
+2019-08-06  Steven G. Kargl  <kargl@gcc.gnu.org>
+
 	PR fortran/42546
 	* check.c(gfc_check_allocated): Add comment pointing to ...
  	* intrinsic.c(sort_actual): ... the checking done here.

gcc/fortran/trans-decl.c

@@ -6449,6 +6449,20 @@ gfc_generate_return (void)
 				    TREE_TYPE (result), DECL_RESULT (fndecl),
 				    result);
 	}
+      else
+	{
+	  /* If the function does not have a result variable, result is
+	     NULL_TREE, and a 'return' is generated without a variable.
+	     The following generates a 'return __result_XXX' where XXX is
+	     the function name.  */
+	  if (sym == sym->result && sym->attr.function)
+	    {
+	      result = gfc_get_fake_result_decl (sym, 0);
+	      result = fold_build2_loc (input_location, MODIFY_EXPR,
+					TREE_TYPE (result),
+					DECL_RESULT (fndecl), result);
+	    }
+	}
     }
 
   return build1_v (RETURN_EXPR, result);

gcc/testsuite/ChangeLog

 2019-08-06  Steven G. Kargl  <kargl@gcc.gnu.org>
 
+	PR fortran/91359
+	* gfortran.dg/pr91359_1.f: New test.
+	* gfortran.dg/pr91359_2.f: Ditto.
+
+2019-08-06  Steven G. Kargl  <kargl@gcc.gnu.org>
+
 	PR fortran/42546
 	* gfortran.dg/allocated_1.f90: New test.
 	* gfortran.dg/allocated_2.f90: Ditto.

gcc/testsuite/gfortran.dg/pr91359_1.f

+! { dg do run }
+! PR fortran/91359
+! Orginal code contributed by Brian T. Carcich <briantcarcich at gmail dot com>
+!
+      logical function zero() result(a)
+         goto 2
+1        return
+2        a = .false.
+         if (.not.a) goto 1
+         return
+      end
+
+      program test_zero
+         logical zero
+         if (zero()) stop 1
+      end

gcc/testsuite/gfortran.dg/pr91359_2.f

+! { dg do run }
+! PR fortran/91359
+! Orginal code contributed by Brian T. Carcich <briantcarcich at gmail dot com>
+!
+      logical function zero() result(a)
+         goto 2
+1        return
+2        a = .false.
+         if (.not.a) goto 1
+         return
+      end
+
+      program test_zero
+         logical zero
+         if (zero()) stop 1
+      end