Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
for trunk and backports?
-- >8 --
This is just the pack version of PR c++/105848, in which our non-dependent
call pruning may cause us to not mark an otherwise unused function pointer
template argument as used.
PR c++/126280
gcc/cp/ChangeLog:
* pt.cc (mark_template_arguments_used): Split out loop into ...
(mark_template_arguments_used_1): ... here. Recurse into
argument packs.
gcc/testsuite/ChangeLog:
* g++.dg/template/fn-ptr6.C: New test.
---
gcc/cp/pt.cc | 11 +++++++++++
gcc/testsuite/g++.dg/template/fn-ptr6.C | 26 +++++++++++++++++++++++++
2 files changed, 37 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/template/fn-ptr6.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 1290db45e182..ced68a238650 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -224,6 +224,7 @@ static bool uses_outer_template_parms (tree);
static tree alias_ctad_tweaks (tree, tree);
static tree inherited_ctad_tweaks (tree, tree, tsubst_flags_t);
static tree deduction_guides_for (tree, bool&, tsubst_flags_t);
+static void mark_template_arguments_used_1 (tree);
/* Make the current scope suitable for access checking when we are
processing T. T can be FUNCTION_DECL for instantiated function
@@ -23738,6 +23739,14 @@ mark_template_arguments_used (tree tmpl, tree args)
/* We already marked outer arguments when specializing the context. */
args = INNERMOST_TEMPLATE_ARGS (args);
+ mark_template_arguments_used_1 (args);
+}
+
+/* Main recursive part of the above. */
+
+static void
+mark_template_arguments_used_1 (tree args)
+{
for (tree arg : tree_vec_range (args))
{
/* A (pointer/reference to) function or variable NTTP argument. */
@@ -23778,6 +23787,8 @@ mark_template_arguments_used (tree tmpl, tree args)
cp_walk_tree_without_duplicates (&DECL_INITIAL (arg),
mark_used_r, nullptr);
}
+ else if (TREE_CODE (arg) == NONTYPE_ARGUMENT_PACK)
+ mark_template_arguments_used_1 (ARGUMENT_PACK_ARGS (arg));
}
}
diff --git a/gcc/testsuite/g++.dg/template/fn-ptr6.C
b/gcc/testsuite/g++.dg/template/fn-ptr6.C
new file mode 100644
index 000000000000..fa111c6d9429
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/fn-ptr6.C
@@ -0,0 +1,26 @@
+// PR c++/126280
+// A version of fn-ptr3a.C where the template parameter is a pack.
+// { dg-do compile { target c++11 } }
+
+template<class T>
+void f(T) { T::fail; } // { dg-error "fail" }
+
+template<void (*...P)(int)>
+struct A {
+ // P not called
+};
+
+template<void (&...P)(char)>
+void wrap() {
+ // P not called
+}
+
+template<int>
+void g() {
+ A<f> a; // { dg-message "required from" }
+ wrap<f>(); // { dg-message "required from" }
+}
+
+int main() {
+ g<0>();
+}
--
2.55.0.329.g48bbf81c29
