OK.
On Fri, Mar 9, 2018 at 12:21 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> On Fri, Mar 09, 2018 at 11:28:47AM -0500, Jason Merrill wrote:
>> On Thu, Mar 8, 2018 at 4:26 PM, Jakub Jelinek <ja...@redhat.com> wrote:
>> > On Thu, Mar 08, 2018 at 04:20:40PM -0500, Jason Merrill wrote:
>> >> On Thu, Mar 8, 2018 at 1:08 PM, Jakub Jelinek <ja...@redhat.com> wrote:
>> >> > The reporter complains that -Wformat incorrectly reports std::string*
>> >> > passed
>> >> > to "%s" format rather than std::string, which is what the user did.
>> >> >
>> >> > This transformation of non-trivial copy init or dtor classes in
>> >> > ellipsis is
>> >> > done by convert_arg_to_ellipsis; that function does many changes and all
>> >> > but this one look desirable for the
>> >> > -Wnonnull/-Wformat/-Wsentinel/-Wrestrict
>> >> > warnings. We prepare a special argument vector in any case, so this
>> >> > patch
>> >> > just arranges to undo what convert_arg_to_ellipsis did for the classes.
>> >> > I think -Wnonnull shouldn't care, because when passing such a class by
>> >> > value, it will be non-NULL (and -Wnonnull looks only for literal NULLs
>> >> > anyway), -Wrestrict only cares about named arguments and -Wsentinel only
>> >> > cares about NULL arguments passed to ellipsis.
>> >>
>> >> I notice that convert_arg_to_ellipsis generates a pointer-typed
>> >> expression, whereas convert_for_arg_passing generates a reference.
>> >> Does correcting that inconsistency help?
>> >
>> > No (though I think it is a good idea anyway).
>>
>> Perhaps then check_format_types could look through REFERENCE_TYPE,
>> since there are no actual expressions of reference type.
>
> It can be done in the caller as well like below, or in c-format.c's
> if (warn_format)
> {
> /* FIXME: Rewrite all the internal functions in this file
> to use the ARGARRAY directly instead of constructing this
> temporary list. */
> tree params = NULL_TREE;
> int i;
> for (i = nargs - 1; i >= 0; i--)
> params = tree_cons (NULL_TREE, argarray[i], params);
> check_format_info (&info, params, arglocs);
> }
> I'm afraid the c-format.c has so many uses of the params list that it is
> hard to tweak it anywhere else.
>
> 2018-03-09 Jason Merrill <ja...@redhat.com>
> Jakub Jelinek <ja...@redhat.com>
>
> PR c++/84076
> * call.c (convert_arg_to_ellipsis): Instead of cp_build_addr_expr
> build ADDR_EXPR with REFERENCE_TYPE.
> (build_over_call): For purposes of check_function_arguments, if
> argarray[j] is ADDR_EXPR with REFERENCE_TYPE created above, use
> its operand rather than the argument itself.
>
> * g++.dg/warn/Wformat-2.C: New test.
>
> --- gcc/cp/call.c.jj 2018-03-09 09:01:32.017423737 +0100
> +++ gcc/cp/call.c 2018-03-09 18:12:34.973494714 +0100
> @@ -7209,7 +7209,7 @@ convert_arg_to_ellipsis (tree arg, tsubs
> "passing objects of non-trivially-copyable "
> "type %q#T through %<...%> is conditionally supported",
> arg_type);
> - return cp_build_addr_expr (arg, complain);
> + return build1 (ADDR_EXPR, build_reference_type (arg_type), arg);
> }
> /* Build up a real lvalue-to-rvalue conversion in case the
> copy constructor is trivial but not callable. */
> @@ -8018,7 +8018,15 @@ build_over_call (struct z_candidate *can
> tree *fargs = (!nargs ? argarray
> : (tree *) alloca (nargs * sizeof (tree)));
> for (j = 0; j < nargs; j++)
> - fargs[j] = maybe_constant_value (argarray[j]);
> + {
> + /* For -Wformat undo the implicit passing by hidden reference
> + done by convert_arg_to_ellipsis. */
> + if (TREE_CODE (argarray[j]) == ADDR_EXPR
> + && TREE_CODE (TREE_TYPE (argarray[j])) == REFERENCE_TYPE)
> + fargs[j] = TREE_OPERAND (argarray[j], 0);
> + else
> + fargs[j] = maybe_constant_value (argarray[j]);
> + }
>
> warned_p = check_function_arguments (input_location, fn, TREE_TYPE
> (fn),
> nargs, fargs, NULL);
> --- gcc/testsuite/g++.dg/warn/Wformat-2.C.jj 2018-03-09 17:59:57.098113181
> +0100
> +++ gcc/testsuite/g++.dg/warn/Wformat-2.C 2018-03-09 17:59:57.098113181
> +0100
> @@ -0,0 +1,17 @@
> +// PR c++/84076
> +// { dg-do compile }
> +// { dg-options "-Wformat" }
> +
> +struct S { ~S (); };
> +struct T { T (); T (const T &); };
> +
> +void
> +foo ()
> +{
> + S s;
> + T t;
> + __builtin_printf ("%s\n", s); // { dg-warning "format '%s' expects
> argument of type 'char\\*', but argument 2 has type 'S'" }
> + __builtin_printf ("%s\n", t); // { dg-warning "format '%s' expects
> argument of type 'char\\*', but argument 2 has type 'T'" }
> + __builtin_printf ("%s\n", &s);// { dg-warning "format '%s' expects
> argument of type 'char\\*', but argument 2 has type 'S\\*'" }
> + __builtin_printf ("%s\n", &t);// { dg-warning "format '%s' expects
> argument of type 'char\\*', but argument 2 has type 'T\\*'" }
> +}
>
>
> Jakub
