2014-02-28 22:52 GMT+01:00 Fabien Chêne <fabien.ch...@gmail.com>:
> 2014-02-28 22:27 GMT+01:00 Jason Merrill <ja...@redhat.com>:
>> Let's change the C++11 diagnostic to match the C++98 diagnostic. So,
>> "uninitialized const member in %q#T" + "%qD should be initialized".
>
> OK.
Hmm, sorry to iterate on this rather trivial issue, but it seems
difficult to mimic the c++98 diagnostic. Actually, the c++98 diagnosic
raises an error at the point of use, mention the class implied, and
add a note at the ref/const member uninitialized. Doing that in c++11
is not currently possible because input_location is sabotaged early in
maybe_explain_implicit_delete (unless there is some magic incantation
in the diagnostic machinery I am not aware of), and the point of use
is lost.
Reading the comment of synthesized_method_walk, which is the only
caller of walk_field_subobs:
"If diag is true, we're either being called from
maybe_explain_implicit_delete to give errors, or if constexpr_p is
non-null, from explain_invalid_constexpr_fn."
I am inclined to think that if we reached one the two functions
mentioned, an error had already been raised and we are trying to
explain why. Thus, it seems to me that only notes should be emitted.
Here we are actually explaining why the default constructor is
deleted, which is a kind of subnote. Hence, I would say that emitting
an error at this point would be seen as a different issue by the user.
All in all, in my opinion, just emitting a note would be appropriate
given the context.
If agreed, the comment above should be adjusted, and says "... called
from maybe_explain_implicit_delete to ***emit additional notes***...",
and the errors raised in callees shall be turned into notes.
Unfortunalely, the comment does not match the code and
synthesized_method_walk is called with diag=true in another context:
/* Warn about calling a non-trivial move assignment in a virtual base. */
if (kind == sfk_move_assignment && !deleted_p && !trivial_p
&& CLASSTYPE_VBASECLASSES (type))
{
location_t loc = input_location;
input_location = DECL_SOURCE_LOCATION (fn);
synthesized_method_walk (type, kind, const_p,
NULL, NULL, NULL, NULL, true,
NULL_TREE, NULL_TREE);
input_location = loc;
}
... Which breaks the logic above, even if it probably intends to reach
this warning later:
warning (OPT_Wvirtual_move_assign,
"defaulted move assignment for %qT calls a non-trivial "
"move assignment operator for virtual base %qT",
ctype, basetype);
This can of revamping I suggest can wait for next stage 1, obviously...
What do you think ?
--
Fabien
