Title
Conditionally-supported behavior for non-POD objects passed to ellipsis
Status
cd1
Section
7.6.1.3 [expr.call]
Submitter
Mike Miller

Created on 2005-04-14.00:00:00 last changed 161 months ago

Messages

Date: 2006-10-15.00:00:00

[Voted into WP at the October, 2006 meeting.]

Date: 2005-10-15.00:00:00

Proposed resolution (October, 2005):

Change 7.6.1.3 [expr.call] paragraph 7 as indicated:

...After these conversions, if the argument does not have arithmetic, enumeration, pointer, pointer to member, or class type, the program is ill-formed. If the argument has a non-POD class type (clause 9), the behavior is undefined. Passing an argument of non-POD class type (clause 9) with no corresponding parameter is conditionally-supported, with implementation-defined semantics.
Date: 2020-12-15.00:00:00

The current wording of 7.6.1.3 [expr.call] paragraph 7 states:

When there is no parameter for a given argument, the argument is passed in such a way that the receiving function can obtain the value of the argument by invoking va_arg (17.13 [support.runtime]). The lvalue-to-rvalue (7.3.2 [conv.lval]), array-to-pointer (7.3.3 [conv.array]), and function-to-pointer (7.3.4 [conv.func]) standard conversions are performed on the argument expression. After these conversions, if the argument does not have arithmetic, enumeration, pointer, pointer to member, or class type, the program is ill-formed. If the argument has a non-POD class type (clause Clause 11 [class]), the behavior is undefined.

Paper J16/04-0167=WG21 N1727 suggests that passing a non-POD object to ellipsis be ill-formed. In discussions at the Lillehammer meeting, however, the CWG felt that the newly-approved category of conditionally-supported behavior would be more appropriate.

History
Date User Action Args
2008-10-05 00:00:00adminsetstatus: wp -> cd1
2007-05-06 00:00:00adminsetstatus: dr -> wp
2006-11-05 00:00:00adminsetmessages: + msg1432
2006-11-05 00:00:00adminsetstatus: ready -> dr
2006-04-22 00:00:00adminsetstatus: review -> ready
2005-10-22 00:00:00adminsetmessages: + msg1232
2005-10-22 00:00:00adminsetstatus: drafting -> review
2005-04-14 00:00:00admincreate