On 08/01/2012 07:35 PM, Jason Merrill wrote:
On 08/01/2012 11:49 AM, Paolo Carlini wrote:
static_assert(sizeof(g<C>(0)) == 2, "Ouch"); // line 11
typedef int testg[sizeof(g<C>(0)) == 2 ? 1 : -1]; // line 13
what happens is that line 13 is mishandled:
sfinae37_red.C:13:48: error: size of array testg is negative
However, *if I comment out line 11*, things work for line 13! If I swap
line 11 and line 13 then the declaration of testg is accepted and the
static_assert triggers.
Curious. I guess that the second time we see the call the compiler
thinks it already has the candidate it needs, but I don't know why
that would be. Are we not getting to type_unification_real from
add_template_candidate the second time?
So, I'm in the middle of this (got distracted earlier today). I can tell
you what I have.
For the second evaluation, the second time we call
instantiate_template_1, thus for the interesting g(int) overload, here:
spec = retrieve_specialization (gen_tmpl, targ_ptr, 0);
gcc_assert (tmpl == gen_tmpl
|| ((fndecl = retrieve_specialization (tmpl, orig_args, 0))
== spec)
|| fndecl == NULL_TREE);
if (spec != NULL_TREE)
{
if (FNDECL_RECHECK_ACCESS_P (spec) && (complain & tf_error))
recheck_decl_substitution (spec, gen_tmpl, targ_ptr);
return spec;
}
things are completely different, because spec != NULL_TREE and, more
importantly, complain is tf_none, thus recheck_decl_substitution is not
called, we just return immediately.
Compare to the first evaluation: in that case we call enforce_access
*way* below, with the perform_deferred_access_checks call near the end
of instantiate_template_1.
Thus, looks like the recheck_decl_substitution mechanism is not working
by design because of complain == tf_none?!?
Note that while I'm debugging this, I see instantiate_template_1 always
getting complain == tf_none, something seems weird about the &&
(complain & tf_error) above...
Paolo.
