https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114867
Nathaniel Shead <nshead at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
CC| |nshead at gcc dot gnu.org
Status|UNCONFIRMED |NEW
Last reconfirmed| |2024-05-25
--- Comment #2 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
Confirmed. The issue is that this part of 'do_nonmember_using_decl' for the
'using std::swap' declaration in the module purview removes the template
candidate and reinserts it to "reveal" it (possibly as newly exported):
if (new_fn == old_fn)
{
/* The function already exists in the current
namespace. We will still want to insert it if
it is revealing a not-revealed thing. */
found = true;
if (!revealing_p)
;
else if (old.using_p ())
{
if (exporting)
/* Update in place. 'tis ok. */
OVL_EXPORT_P (old.get_using ()) = true;
;
}
else if (DECL_MODULE_EXPORT_P (new_fn))
;
else
{
value = old.remove_node (value);
found = false;
}
break;
}
// ...
if (!found && insert_p)
/* Unlike the decl-pushing case we don't drop anticipated
builtins here. They don't cause a problem, and we'd
like to match them with a future declaration. */
value = ovl_insert (new_fn, value, 1 + exporting);
However, within the 'shared_ptr::swap' template it's already holding a pointer
to the OVERLOAD, and the 'remove_node' call drops it from this existing
overload set but the 'ovl_insert' doesn't add it back to that set, rather
returning a new one.
I suppose a fix is possibly to ensure that we only do this update in-place but
I don't know if that'll work with OVL_HIDDEN declarations, since they need to
always be kept at the front of the list, and reordering might still cause the
same issues.
