On Mon, Jan 18, 2016 at 11:17:04AM -0500, Jason Merrill wrote:
> But we do currently print
>
> wa.C:1:24: warning: unused parameter ‘xs#0’ [-Wunused-parameter]
> wa.C:1:24: warning: unused parameter ‘xs#1’ [-Wunused-parameter]
> wa.C:1:24: warning: unused parameter ‘xs#2’ [-Wunused-parameter]
>
> for that testcase, and I think your patch would remove this warning as well.
Right. How about this instead? In this version, I only set TREE_USED when
we actually use the pack, so we'll keep the warning for the testcase above.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2016-01-19 Marek Polacek <pola...@redhat.com>
PR c++/68965
* pt.c (tsubst_copy): Mark elements in expanded vector as used.
* g++.dg/cpp1y/parameter-pack-1.C: New test.
* g++.dg/cpp1y/parameter-pack-2.C: New test.
diff --git gcc/cp/pt.c gcc/cp/pt.c
index 866b4b1..6062ebe 100644
--- gcc/cp/pt.c
+++ gcc/cp/pt.c
@@ -14010,7 +14010,12 @@ tsubst_copy (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
--c_inhibit_evaluation_warnings;
if (TREE_CODE (expanded) == TREE_VEC)
- len = TREE_VEC_LENGTH (expanded);
+ {
+ len = TREE_VEC_LENGTH (expanded);
+ /* Set TREE_USED for the benefit of -Wunused. */
+ for (int i = 0; i < len; i++)
+ TREE_USED (TREE_VEC_ELT (expanded, i)) = true;
+ }
if (expanded == error_mark_node)
return error_mark_node;
diff --git gcc/testsuite/g++.dg/cpp1y/parameter-pack-1.C
gcc/testsuite/g++.dg/cpp1y/parameter-pack-1.C
index e69de29..27a6bf9 100644
--- gcc/testsuite/g++.dg/cpp1y/parameter-pack-1.C
+++ gcc/testsuite/g++.dg/cpp1y/parameter-pack-1.C
@@ -0,0 +1,23 @@
+// PR c++/68965
+// { dg-do compile { target c++14 } }
+// { dg-options "-Wall -Wextra" }
+
+auto count = [](auto&&... xs)
+{
+ return sizeof...(xs);
+};
+
+struct count_struct
+{
+ template<typename... Ts>
+ auto operator()(Ts&&... xs)
+ {
+ return sizeof...(xs);
+ }
+};
+
+int main()
+{
+ count(1,2,3);
+ count_struct{}(1,2,3);
+}
diff --git gcc/testsuite/g++.dg/cpp1y/parameter-pack-2.C
gcc/testsuite/g++.dg/cpp1y/parameter-pack-2.C
index e69de29..9520875 100644
--- gcc/testsuite/g++.dg/cpp1y/parameter-pack-2.C
+++ gcc/testsuite/g++.dg/cpp1y/parameter-pack-2.C
@@ -0,0 +1,21 @@
+// PR c++/68965
+// { dg-do compile { target c++14 } }
+// { dg-options "-Wall -Wextra" }
+
+auto count = [](auto&&... xs) // { dg-warning "unused parameter" }
+{
+};
+
+struct count_struct
+{
+ template<typename... Ts>
+ auto operator()(Ts&&... xs) // { dg-warning "unused parameter" }
+ {
+ }
+};
+
+int main()
+{
+ count(1,2,3);
+ count_struct{}(1,2,3);
+}
Marek
