I am friendly pinging the patch below ...
Dodji Seketeli <do...@redhat.com> a écrit:
> Hello,
>
> Consider this example:
>
> 1 template<class...I> struct List {};
> 2 template<int T> struct Z {static const int value = T;};
> 3 template<int...T> using LZ = List<Z<T>...>;
> 4
> 5 template<class...U>
> 6 struct F
> 7 {
> 8 using N = LZ<U::value...>; //#1 This should amount to
> List<Z<U::value>...>
> 9 }
> 10
> 11 F<Z<1>, Z<2> >::N A; //#2
>
> which G++ fails to compile, with this error message:
>
> test-PR53609-3.cc: In instantiation of 'struct F<Z<1>, Z<2> >':
> test-PR53609-3.cc:11:15: required from here
> test-PR53609-3.cc:3:43: error: wrong number of template arguments (2, should
> be 1)
> template<int...T> using LZ = List<Z<T>...>;
> ^
> test-PR53609-3.cc:2:24: error: provided for 'template<int T> struct Z'
> template<int T> struct Z {static const int value = T;};
>
> I think this is because in #1, when we substitute the argument pack
> {U::value...} into the pack expansion Z<T>..., tsubst_pack_expansion
> yields Z<U::value...>, instead of Z<U::value>..., so the instantiation
> of LZ amounts to List<Z<U::value...> >, instead of
> List<Z<U::value>...>.
>
> The idea of this patch is to make tsubst_pack_expansion support
> substituting an argument pack (into a pack expansion) where one of the
> arguments (let's call it the Ith argument) is itself a pack expansion
> P. In that case, the Ith element resulting from the substituting
> should be a pack expansion P'.
>
> The pattern of P' is then the pattern of P into which the pattern of
> the Ith argument of the argument pack has been substituted.
>
> Tested on x86_64-unknown-linux-gnu against trunk.
>
> gcc/cp/
>
> * pt.c (real_argument_pack_element_p)
> (any_non_real_argument_pack_element_p)
> (arg_pack_select_for_pack_expansion)
> (set_arg_pack_select_index_for_pack_expansion): New static
> functions.
> (has_bare_parameter_packs): Factorized out of ...
> (check_for_bare_parameter_packs): ... here.
> (tsubst_pack_expansion): Support substituting an argument pack
> that contains a pack expansion.
>
> gcc/testsuite/
>
> * g++.dg/cpp0x/variadic139.C: New test.
> * g++.dg/cpp0x/variadic140.C: Likewise.
> * g++.dg/cpp0x/variadic141.C: Likewise.
> ---
> gcc/cp/pt.c | 151
> ++++++++++++++++++++++++------
> gcc/testsuite/g++.dg/cpp0x/variadic139.C | 14 +++
> gcc/testsuite/g++.dg/cpp0x/variadic140.C | 22 +++++
> gcc/testsuite/g++.dg/cpp0x/variadic141.C | 22 +++++
> 4 files changed, 182 insertions(+), 27 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic139.C
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic140.C
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic141.C
>
> diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
> index 16952bf..bcfe83f 100644
> --- a/gcc/cp/pt.c
> +++ b/gcc/cp/pt.c
> @@ -3310,6 +3310,29 @@ make_pack_expansion (tree arg)
> return result;
> }
>
> +/* Return NULL_TREE iff T contains *NO* unexpanded parameter packs.
> + Return the TREE_LIST of unexpanded parameter packs otherwise. */
> +
> +static tree
> +has_bare_parameter_packs (tree t)
> +{
> + tree parameter_packs = NULL_TREE;
> + struct find_parameter_pack_data ppd;
> +
> + if (!processing_template_decl || !t || t == error_mark_node)
> + return NULL_TREE;
> +
> + if (TREE_CODE (t) == TYPE_DECL)
> + t = TREE_TYPE (t);
> +
> + ppd.parameter_packs = ¶meter_packs;
> + ppd.visited = pointer_set_create ();
> + cp_walk_tree (&t, &find_parameter_packs_r, &ppd, ppd.visited);
> + pointer_set_destroy (ppd.visited);
> +
> + return parameter_packs;
> +}
> +
> /* Checks T for any "bare" parameter packs, which have not yet been
> expanded, and issues an error if any are found. This operation can
> only be done on full expressions or types (e.g., an expression
> @@ -3327,19 +3350,7 @@ make_pack_expansion (tree arg)
> bool
> check_for_bare_parameter_packs (tree t)
> {
> - tree parameter_packs = NULL_TREE;
> - struct find_parameter_pack_data ppd;
> -
> - if (!processing_template_decl || !t || t == error_mark_node)
> - return false;
> -
> - if (TREE_CODE (t) == TYPE_DECL)
> - t = TREE_TYPE (t);
> -
> - ppd.parameter_packs = ¶meter_packs;
> - ppd.visited = pointer_set_create ();
> - cp_walk_tree (&t, &find_parameter_packs_r, &ppd, ppd.visited);
> - pointer_set_destroy (ppd.visited);
> + tree parameter_packs = has_bare_parameter_packs (t);
>
> if (parameter_packs)
> {
> @@ -9065,6 +9076,86 @@ make_fnparm_pack (tree spec_parm)
> return extract_fnparm_pack (NULL_TREE, &spec_parm);
> }
>
> +/* Return true iff the Ith element of the argument pack ARG_PACK is
> + *NOT* a pack expansion. */
> +
> +static bool
> +real_argument_pack_element_p (tree arg_pack, int i)
> +{
> + return !PACK_EXPANSION_P (TREE_VEC_ELT
> + (ARGUMENT_PACK_ARGS (arg_pack), i));
> +}
> +
> +/* Return true iff ARG_PACK is an argument pack that contains a pack
> + expansion. */
> +
> +static bool
> +any_non_real_argument_pack_element_p (tree arg_pack)
> +{
> + if (arg_pack == NULL_TREE
> + || arg_pack == error_mark_node
> + || !ARGUMENT_PACK_P (arg_pack))
> + return false;
> +
> + for (int i = 0; i < TREE_VEC_LENGTH (ARGUMENT_PACK_ARGS (arg_pack)); ++i)
> + if (!real_argument_pack_element_p (arg_pack, i))
> + return true;
> + return false;
> +}
> +
> +/* Creates an ARGUMENT_PACK_SELECT tree node, for the purpose of
> + substituting an argument pack into a pack expansion. This is a
> + subroutine of tsubst_pack_expansion. */
> +
> +static tree
> +arg_pack_select_for_pack_expansion (tree arg_pack)
> +{
> + tree aps = make_node (ARGUMENT_PACK_SELECT);
> +
> + if (!any_non_real_argument_pack_element_p (arg_pack))
> + ARGUMENT_PACK_SELECT_FROM_PACK (aps) = arg_pack;
> + else
> + {
> + tree tmp_arg_pack = TYPE_P (arg_pack)
> + ? cxx_make_type (TREE_CODE (arg_pack))
> + : make_node (TREE_CODE (arg_pack));
> + tree tmp_vec =
> + make_tree_vec (TREE_VEC_LENGTH (ARGUMENT_PACK_ARGS (arg_pack)));
> + SET_ARGUMENT_PACK_ARGS (tmp_arg_pack, tmp_vec);
> + ARGUMENT_PACK_SELECT_FROM_PACK (aps) = tmp_arg_pack;
> + }
> +
> + return aps;
> +}
> +
> +/* Setup APS, which is an instance of an ARGUMENT_PACK_SELECT tree, so
> + that it selects the Ith argument out of the argument pack
> + ARG_PACK. If the Ith argument is a pack expansion, then just
> + select its pattern. Otherwise, select the whole argument. This
> + is a subroutine of tsubst_pack_expansion. */
> +
> +static void
> +set_arg_pack_select_index_for_pack_expansion (tree aps,
> + int i,
> + tree arg_pack)
> +{
> + if (any_non_real_argument_pack_element_p (arg_pack))
> + {
> + tree args_vec =
> + ARGUMENT_PACK_ARGS (ARGUMENT_PACK_SELECT_FROM_PACK (aps));
> + if (real_argument_pack_element_p (arg_pack, i))
> + TREE_VEC_ELT (args_vec, i) =
> + TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack), i);
> + else
> + TREE_VEC_ELT (args_vec, i) =
> + PACK_EXPANSION_PATTERN (TREE_VEC_ELT
> + (ARGUMENT_PACK_ARGS (arg_pack),
> + i));
> + }
> +
> + ARGUMENT_PACK_SELECT_INDEX (aps) = i;
> +}
> +
> /* Substitute ARGS into T, which is an pack expansion
> (i.e. TYPE_PACK_EXPANSION or EXPR_PACK_EXPANSION). Returns a
> TREE_VEC with the substituted arguments, a PACK_EXPANSION_* node
> @@ -9284,20 +9375,21 @@ tsubst_pack_expansion (tree t, tree args,
> tsubst_flags_t complain,
> for (pack = packs; pack; pack = TREE_CHAIN (pack))
> {
> tree parm = TREE_PURPOSE (pack);
> - tree arg;
> + tree arg_pack = TREE_VALUE (pack);
> + tree aps; /* instance of ARGUMENT_PACK_SELECT
> + tree. */
>
> /* Select the Ith argument from the pack. */
> if (TREE_CODE (parm) == PARM_DECL)
> {
> if (i == 0)
> {
> - arg = make_node (ARGUMENT_PACK_SELECT);
> - ARGUMENT_PACK_SELECT_FROM_PACK (arg) = TREE_VALUE (pack);
> + aps = arg_pack_select_for_pack_expansion (arg_pack);
> mark_used (parm);
> - register_local_specialization (arg, parm);
> + register_local_specialization (aps, parm);
> }
> else
> - arg = retrieve_local_specialization (parm);
> + aps = retrieve_local_specialization (parm);
> }
> else
> {
> @@ -9306,25 +9398,30 @@ tsubst_pack_expansion (tree t, tree args,
> tsubst_flags_t complain,
>
> if (i == 0)
> {
> - arg = make_node (ARGUMENT_PACK_SELECT);
> - ARGUMENT_PACK_SELECT_FROM_PACK (arg) = TREE_VALUE (pack);
> + aps = arg_pack_select_for_pack_expansion (arg_pack);
> /* Update the corresponding argument. */
> - TMPL_ARG (args, level, idx) = arg;
> + TMPL_ARG (args, level, idx) = aps;
> }
> else
> /* Re-use the ARGUMENT_PACK_SELECT. */
> - arg = TMPL_ARG (args, level, idx);
> + aps = TMPL_ARG (args, level, idx);
> }
> - ARGUMENT_PACK_SELECT_INDEX (arg) = i;
> + set_arg_pack_select_index_for_pack_expansion (aps, i,
> + arg_pack);
> }
>
> /* Substitute into the PATTERN with the altered arguments. */
> if (!TYPE_P (pattern))
> - TREE_VEC_ELT (result, i) =
> - tsubst_expr (pattern, args, complain, in_decl,
> - /*integral_constant_expression_p=*/false);
> + t = tsubst_expr (pattern, args, complain, in_decl,
> + /*integral_constant_expression_p=*/false);
> else
> - TREE_VEC_ELT (result, i) = tsubst (pattern, args, complain, in_decl);
> + t = tsubst (pattern, args, complain, in_decl);
> +
> + /* If the Ith argument pack element is a pack expansion, then
> + the Ith element resulting from the substituting is going to
> + be a pack expansion as well. */
> + TREE_VEC_ELT (result, i) =
> + (has_bare_parameter_packs (t)) ? make_pack_expansion (t) : t;
>
> if (TREE_VEC_ELT (result, i) == error_mark_node)
> {
> diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic139.C
> b/gcc/testsuite/g++.dg/cpp0x/variadic139.C
> new file mode 100644
> index 0000000..89f7b32
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/variadic139.C
> @@ -0,0 +1,14 @@
> +// Origin: PR c++/53609
> +// { dg-do compile { target c++11 } }
> +
> +template<class...I> struct List {};
> +template<int T> struct Z {static const int value = T;};
> +template<int...T> using LZ = List<Z<T>...>;
> +
> +template<class...U>
> +struct F
> +{
> + using N = LZ<U::value...>;
> +};
> +
> +F<Z<1>, Z<2> >::N A;
> diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic140.C
> b/gcc/testsuite/g++.dg/cpp0x/variadic140.C
> new file mode 100644
> index 0000000..17ca9e5
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/variadic140.C
> @@ -0,0 +1,22 @@
> +// Origin: PR c++/53609
> +// { dg-do compile { target c++11 } }
> +
> +template<class...I> struct List{ static const bool is_ok = false;};
> +template<int T> struct Z
> +{
> + static const int value = T;
> + static const int value_square = T * T;
> +};
> +
> +template<template<int> class U>
> +struct List<U<2>, U<3>, U<4>, U<9>> { static const bool is_ok = true;};
> +
> +template<int...T> using LZ = List<Z<T>...>;
> +
> +template<class...T>
> +struct F
> +{
> + using N = LZ<T::value..., T::value_square...>;
> +};
> +
> +static_assert (F<Z<2>, Z<3>>::N::is_ok, "");
> diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic141.C
> b/gcc/testsuite/g++.dg/cpp0x/variadic141.C
> new file mode 100644
> index 0000000..6b893a7
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/variadic141.C
> @@ -0,0 +1,22 @@
> +// Origin: PR c++/53609
> +// { dg-do compile { target c++11 } }
> +
> +template<class...I> struct List{ static const bool is_ok = false;};
> +template<int T> struct Z
> +{
> + static const int value = T;
> + static const int value_square = T * T;
> +};
> +
> +template<template<int> class U>
> +struct List<U<2>, U<3>, U<4>, U<9>> { static const bool is_ok = true;};
> +
> +template<int...T> using LZ = List<Z<T>...>;
> +
> +template<class...T>
> +struct F
> +{
> + using N = LZ<T::value..., Z<4>::value, Z<9>::value>;
> +};
> +
> +static_assert (F<Z<2>, Z<3>>::N::is_ok, "");
--
Dodji
