During overload resolution, we sometimes outright ignore a function from
the overload set and leave no trace of it in the candidates list, for
example when we find a perfect non-template candidate we discard all
function templates, or when the callee is a template-id we discard all
non-template functions. We should still however make note of these
unviable functions when diagnosing overload resolution failure, but
that's not possible if they're not present in the returned candidates
list.
To that end, this patch reworks add_candidates to add such ignored
functions to the list. The new rr_ignored rejection reason is somewhat
of a catch-all; we could perhaps split it up into more specific rejection
reasons, but I leave that as future work.
gcc/cp/ChangeLog:
* call.cc (enum rejection_reason_code): Add rr_ignored.
(add_ignored_candidate): Define.
(ignored_candidate_p): Define.
(add_template_candidate_real): Do add_ignored_candidate
instead of returning NULL.
(splice_viable): Put ignored (unviable) candidates last.
(print_z_candidate): Handle ignored candidates.
(build_new_function_call): Refine shortcut that calls
cp_build_function_call_vec now that non-templates can
appear in the candidate list for a template-id call.
(add_candidates): Replace 'bad_fns' overload with 'bad_cands'
candidate list. When not considering a candidate, add it
to the list as an ignored candidate. Add all 'bad_cands'
to the overload set as well.
gcc/testsuite/ChangeLog:
* g++.dg/diagnostic/param-type-mismatch-2.C: Rename template
function test_7 that accidentally (perhaps) shares the same
name as its non-template callee.
* g++.dg/overload/error6.C: New test.
---
gcc/cp/call.cc| 149 +-
.../g++.dg/diagnostic/param-type-mismatch-2.C | 20 +--
gcc/testsuite/g++.dg/overload/error6.C| 9 ++
3 files changed, 132 insertions(+), 46 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/overload/error6.C
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index 89d422f7220..3212d5268e0 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -441,7 +441,8 @@ enum rejection_reason_code {
rr_template_unification,
rr_invalid_copy,
rr_inherited_ctor,
- rr_constraint_failure
+ rr_constraint_failure,
+ rr_ignored,
};
struct conversion_info {
@@ -2224,6 +2225,34 @@ add_candidate (struct z_candidate **candidates,
return cand;
}
+/* FN is a function from the overload set that we outright didn't even consider
+ (for some reason); add it to the list as an unviable "ignored" candidate.
*/
+
+static z_candidate *
+add_ignored_candidate (z_candidate **candidates, tree fn)
+{
+ /* No need to dynamically allocate these. */
+ static const rejection_reason reason_ignored = { rr_ignored, {} };
+
+ struct z_candidate *cand = (struct z_candidate *)
+conversion_obstack_alloc (sizeof (struct z_candidate));
+
+ cand->fn = fn;
+ cand->reason = const_cast (_ignored);
+ cand->next = *candidates;
+ *candidates = cand;
+
+ return cand;
+}
+
+/* True iff CAND is a candidate added by add_ignored_candidate. */
+
+static bool
+ignored_candidate_p (const z_candidate *cand)
+{
+ return cand->reason && cand->reason->code == rr_ignored;
+}
+
/* Return the number of remaining arguments in the parameter list
beginning with ARG. */
@@ -3471,7 +3500,7 @@ add_template_candidate_real (struct z_candidate
**candidates, tree tmpl,
}
if (len < skip_without_in_chrg)
-return NULL;
+return add_ignored_candidate (candidates, tmpl);
if (DECL_CONSTRUCTOR_P (tmpl) && nargs == 2
&& same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (first_arg),
@@ -3609,7 +3638,7 @@ add_template_candidate_real (struct z_candidate
**candidates, tree tmpl,
if (((flags & (LOOKUP_ONLYCONVERTING|LOOKUP_LIST_INIT_CTOR))
== LOOKUP_ONLYCONVERTING)
&& DECL_NONCONVERTING_P (fn))
-return NULL;
+return add_ignored_candidate (candidates, fn);
if (DECL_CONSTRUCTOR_P (fn) && nargs == 2)
{
@@ -3724,6 +3753,9 @@ splice_viable (struct z_candidate *cands,
z_candidate *unviable = nullptr;
z_candidate **unviable_tail =
+ z_candidate *unviable_ignored = nullptr;
+ z_candidate **unviable_ignored_tail = _ignored;
+
/* Be strict inside templates, since build_over_call won't actually
do the conversions to get pedwarns. */
if (processing_template_decl)
@@ -3742,6 +3774,7 @@ splice_viable (struct z_candidate *cands,
its viability. */
auto& tail = (cand->viable == 1 ? strictly_viable_tail
: cand->viable == -1 ? non_strictly_viable_tail
+ : ignored_candidate_p (cand) ? unviable_ignored_tail
: unviable_tail);
*tail = cand;
tail = >next;
@@ -3751,7 +3784,8 @@ splice_viable (struct z_candidate *cands,
