@@ -201,7 +201,6 @@ static void append_type_to_template_for_access_check_1 (tree, tree, tree,
static tree listify (tree);
static tree listify_autos (tree, tree);
static tree template_parm_to_arg (tree t);
-static bool arg_from_parm_pack_p (tree, tree);
static tree current_template_args (void);
static tree tsubst_template_parm (tree, tree, tsubst_flags_t);
static tree instantiate_alias_template (tree, tree, tsubst_flags_t);
@@ -3816,42 +3815,6 @@ template_parm_to_arg (tree t)
return t;
}
-/* This function returns TRUE if PARM_PACK is a template parameter
- pack and if ARG_PACK is what template_parm_to_arg returned when
- passed PARM_PACK. */
-
-static bool
-arg_from_parm_pack_p (tree arg_pack, tree parm_pack)
-{
- /* For clarity in the comments below let's use the representation
- argument_pack<elements>' to denote an argument pack and its
- elements.
-
- In the 'if' block below, we want to detect cases where
- ARG_PACK is argument_pack<PARM_PACK...>. I.e, we want to
- check if ARG_PACK is an argument pack which sole element is
- the expansion of PARM_PACK. That argument pack is typically
- created by template_parm_to_arg when passed a parameter
- pack. */
-
- if (arg_pack
- && TREE_VEC_LENGTH (ARGUMENT_PACK_ARGS (arg_pack)) == 1
- && PACK_EXPANSION_P (TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack), 0)))
- {
- tree expansion = TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack), 0);
- tree pattern = PACK_EXPANSION_PATTERN (expansion);
- if ((TYPE_P (pattern) && same_type_p (pattern, parm_pack))
- || (!TYPE_P (pattern) && cp_tree_equal (parm_pack, pattern)))
- /* The argument pack that the parameter maps to is just an
- expansion of the parameter itself, such as one would
- find in the implicit typedef of a class inside the
- class itself. Consider this parameter "unsubstituted",
- so that we will maintain the outer pack expansion. */
- return true;
- }
- return false;
-}
-
/* Given a set of template parameters, return them as a set of template
arguments. The template parameters are represented as a TREE_VEC, in
the form documented in cp-tree.h for template arguments. */
@@ -9148,6 +9111,168 @@ 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 a
+ pack expansion. */
+
+static bool
+argument_pack_element_is_expansion_p (tree arg_pack, int i)
+{
+ tree vec = ARGUMENT_PACK_ARGS (arg_pack);
+ if (i >= TREE_VEC_LENGTH (vec))
+ return false;
+ return PACK_EXPANSION_P (TREE_VEC_ELT (vec, i));
+}
+
+
+/* Creates and return an ARGUMENT_PACK_SELECT tree node. */
+
+static tree
+make_argument_pack_select (tree arg_pack, unsigned index)
+{
+ tree aps = make_node (ARGUMENT_PACK_SELECT);
+
+ ARGUMENT_PACK_SELECT_FROM_PACK (aps) = arg_pack;
+ ARGUMENT_PACK_SELECT_INDEX (aps) = index;
+
+ return aps;
+}
+
+/* This is a subroutine of tsubst_pack_expansion.
+
+ It returns TRUE if we need to use the PACK_EXPANSION_EXTRA_ARGS
+ mechanism to store the (non complete list of) arguments of the
+ substitution and return a non substituted pack expansion, in order
+ to wait for when we have enough arguments to really perform the
+ substitution. */
+
+static bool
+use_pack_expansion_extra_args_p (tree parm_packs,
+ int arg_pack_len,
+ bool has_empty_arg)
+{
+ if (parm_packs == NULL_TREE)
+ return false;
+
+ bool has_expansion_arg = false;
+ for (int i = 0 ; i < arg_pack_len; ++i)
+ {
+ bool has_non_expansion_arg = false;
+ for (tree parm_pack = parm_packs;
+ parm_pack;
+ parm_pack = TREE_CHAIN (parm_pack))
+ {
+ tree arg = TREE_VALUE (parm_pack);
+
+ if (argument_pack_element_is_expansion_p (arg, i))
+ has_expansion_arg = true;
+ else
+ has_non_expansion_arg = true;
+ }
+
+ /* If one pack has an expansion and another pack has a normal
+ argument or if one pack has an empty argument another one
+ hasn't then tsubst_pack_expansion cannot perform the
+ substitution and need to fall back on the
+ PACK_EXPANSION_EXTRA mechanism. */
+ if ((has_expansion_arg && has_non_expansion_arg)
+ || (has_empty_arg && (has_expansion_arg || has_non_expansion_arg)))
+ return true;
+ }
+ return false;
+}
+
+/* [temp.variadic]/6 says that:
+
+ The instantiation of a pack expansion [...]
+ produces a list E1,E2, ..., En, where N is the number of elements
+ in the pack expansion parameters.
+
+ This subroutine of tsubst_pack_expansion produces one of these Ei.
+
+ PATTERN is the pattern of the pack expansion. PARM_PACKS is a
+ TREE_LIST in which each TREE_PURPOSE is a parameter pack of
+ PATTERN, and each TREE_VALUE is its corresponding argument pack.
+ INDEX is the index 'i' of the element Ei to produce. ARGS,
+ COMPLAIN, and IN_DECL are the same parameters as for the
+ tsubst_pack_expansion function.
+
+ The function returns the resulting Ei upon successful completion,
+ or error_mark_node.
+
+ Note that this function possibly modifies the ARGS parameter, so
+ it's the responsibility of the caller to restore it. */
+
+static tree
+gen_elem_of_pack_expansion_instantiation (tree pattern,
+ tree parm_packs,
+ unsigned index,
+ tree args /* This parm gets
+ modified. */,
+ tsubst_flags_t complain,
+ tree in_decl)
+{
+ tree t;
+ bool ith_elem_is_expansion = false;
+
+ /* For each parameter pack, change the substitution of the parameter
+ pack to the ith argument in its argument pack, then expand the
+ pattern. */
+ for (tree pack = parm_packs; pack; pack = TREE_CHAIN (pack))
+ {
+ tree parm = TREE_PURPOSE (pack);
+ tree arg_pack = TREE_VALUE (pack);
+ tree aps; /* instance of ARGUMENT_PACK_SELECT. */
+
+ ith_elem_is_expansion |=
+ PACK_EXPANSION_P (TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack),
+ index));
+ /* Select the Ith argument from the pack. */
+ if (TREE_CODE (parm) == PARM_DECL)
+ {
+ if (index == 0)
+ {
+ aps = make_argument_pack_select (arg_pack, index);
+ mark_used (parm);
+ register_local_specialization (aps, parm);
+ }
+ else
+ aps = retrieve_local_specialization (parm);
+ }
+ else
+ {
+ int idx, level;
+ template_parm_level_and_index (parm, &level, &idx);
+
+ if (index == 0)
+ {
+ aps = make_argument_pack_select (arg_pack, index);
+ /* Update the corresponding argument. */
+ TMPL_ARG (args, level, idx) = aps;
+ }
+ else
+ /* Re-use the ARGUMENT_PACK_SELECT. */
+ aps = TMPL_ARG (args, level, idx);
+ }
+ ARGUMENT_PACK_SELECT_INDEX (aps) = index;
+ }
+
+ /* Substitute into the PATTERN with the (possibly altered)
+ arguments. */
+ if (!TYPE_P (pattern))
+ t = tsubst_expr (pattern, args, complain, in_decl,
+ /*integral_constant_expression_p=*/false);
+ else
+ 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. */
+ if (ith_elem_is_expansion)
+ t = make_pack_expansion (t);
+
+ return t;
+}
+
/* 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
@@ -9160,8 +9285,6 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
tree pattern;
tree pack, packs = NULL_TREE;
bool unsubstituted_packs = false;
- bool real_packs = false;
- int missing_level = 0;
int i, len = -1;
tree result;
struct pointer_map_t *saved_local_specializations = NULL;
@@ -9240,14 +9363,6 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
return result;
}
- if (arg_from_parm_pack_p (arg_pack, parm_pack))
- /* The argument pack that the parameter maps to is just an
- expansion of the parameter itself, such as one would find
- in the implicit typedef of a class inside the class itself.
- Consider this parameter "unsubstituted", so that we will
- maintain the outer pack expansion. */
- arg_pack = NULL_TREE;
-
if (arg_pack)
{
int my_len =
@@ -9275,13 +9390,6 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
return error_mark_node;
}
- if (TREE_VEC_LENGTH (ARGUMENT_PACK_ARGS (arg_pack)) == 1
- && PACK_EXPANSION_P (TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack),
- 0)))
- /* This isn't a real argument pack yet. */;
- else
- real_packs = true;
-
/* Keep track of the parameter packs and their corresponding
argument packs. */
packs = tree_cons (parm_pack, arg_pack, packs);
@@ -9293,59 +9401,39 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
well as the missing_level counter because function parameter
packs don't have a level. */
unsubstituted_packs = true;
- if (!missing_level || missing_level > level)
- missing_level = level;
}
}
+ /* Do we need to use the PACK_EXPANSION_EXTRA_ARGS mechanism? */
+ bool use_pack_expansion_extra_args =
+ use_pack_expansion_extra_args_p (packs, len, unsubstituted_packs);
+
/* We cannot expand this expansion expression, because we don't have
all of the argument packs we need. */
- if (unsubstituted_packs)
+ if (use_pack_expansion_extra_args)
{
- if (real_packs)
- {
- /* We got some full packs, but we can't substitute them in until we
- have values for all the packs. So remember these until then. */
- tree save_args;
-
- t = make_pack_expansion (pattern);
+ /* We got some full packs, but we can't substitute them in until we
+ have values for all the packs. So remember these until then. */
- /* The call to add_to_template_args above assumes no overlap
- between saved args and new args, so prune away any fake
- args, i.e. those that satisfied arg_from_parm_pack_p above. */
- if (missing_level && levels >= missing_level)
- {
- gcc_assert (TMPL_ARGS_HAVE_MULTIPLE_LEVELS (args)
- && missing_level > 1);
- TREE_VEC_LENGTH (args) = missing_level - 1;
- save_args = copy_node (args);
- TREE_VEC_LENGTH (args) = levels;
- }
- else
- save_args = args;
-
- PACK_EXPANSION_EXTRA_ARGS (t) = save_args;
- }
+ t = make_pack_expansion (pattern);
+ PACK_EXPANSION_EXTRA_ARGS (t) = args;
+ return t;
+ }
+ else if (unsubstituted_packs)
+ {
+ /* There were no real arguments, we're just replacing a parameter
+ pack with another version of itself. Substitute into the
+ pattern and return a PACK_EXPANSION_*. The caller will need to
+ deal with that. */
+ if (TREE_CODE (t) == EXPR_PACK_EXPANSION)
+ t = tsubst_expr (pattern, args, complain, in_decl,
+ /*integral_constant_expression_p=*/false);
else
- {
- /* There were no real arguments, we're just replacing a parameter
- pack with another version of itself. Substitute into the
- pattern and return a PACK_EXPANSION_*. The caller will need to
- deal with that. */
- if (TREE_CODE (t) == EXPR_PACK_EXPANSION)
- t = tsubst_expr (pattern, args, complain, in_decl,
- /*integral_constant_expression_p=*/false);
- else
- t = tsubst (pattern, args, complain, in_decl);
- t = make_pack_expansion (t);
- }
+ t = tsubst (pattern, args, complain, in_decl);
+ t = make_pack_expansion (t);
return t;
}
- /* We could not find any argument packs that work. */
- if (len < 0)
- return error_mark_node;
-
if (need_local_specializations)
{
/* We're in a late-specified return type, so create our own local
@@ -9361,55 +9449,12 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
result = make_tree_vec (len);
for (i = 0; i < len; ++i)
{
- /* For parameter pack, change the substitution of the parameter
- pack to the ith argument in its argument pack, then expand
- the pattern. */
- for (pack = packs; pack; pack = TREE_CHAIN (pack))
- {
- tree parm = TREE_PURPOSE (pack);
- tree arg;
-
- /* 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);
- mark_used (parm);
- register_local_specialization (arg, parm);
- }
- else
- arg = retrieve_local_specialization (parm);
- }
- else
- {
- int idx, level;
- template_parm_level_and_index (parm, &level, &idx);
-
- if (i == 0)
- {
- arg = make_node (ARGUMENT_PACK_SELECT);
- ARGUMENT_PACK_SELECT_FROM_PACK (arg) = TREE_VALUE (pack);
- /* Update the corresponding argument. */
- TMPL_ARG (args, level, idx) = arg;
- }
- else
- /* Re-use the ARGUMENT_PACK_SELECT. */
- arg = TMPL_ARG (args, level, idx);
- }
- ARGUMENT_PACK_SELECT_INDEX (arg) = i;
- }
-
- /* 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);
- else
- TREE_VEC_ELT (result, i) = tsubst (pattern, args, complain, in_decl);
-
- if (TREE_VEC_ELT (result, i) == error_mark_node)
+ t = gen_elem_of_pack_expansion_instantiation (pattern, packs,
+ i,
+ args, complain,
+ in_decl);
+ TREE_VEC_ELT (result, i) = t;
+ if (t == error_mark_node)
{
result = error_mark_node;
break;
@@ -9427,6 +9472,10 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
else
{
int idx, level;
+
+ if (TREE_VALUE (pack) == NULL_TREE)
+ continue;
+
template_parm_level_and_index (parm, &level, &idx);
/* Update the corresponding argument. */
@@ -11163,8 +11212,24 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl)
arg = TMPL_ARG (args, level, idx);
if (arg && TREE_CODE (arg) == ARGUMENT_PACK_SELECT)
- /* See through ARGUMENT_PACK_SELECT arguments. */
- arg = ARGUMENT_PACK_SELECT_ARG (arg);
+ {
+ /* See through ARGUMENT_PACK_SELECT arguments. */
+ arg = ARGUMENT_PACK_SELECT_ARG (arg);
+ /* If the selected argument is an expansion E, that most
+ likely means we were called from
+ gen_elem_of_pack_expansion_instantiation during the
+ substituting of pack an argument pack (which Ith
+ element is a pack expansion, where I is
+ ARGUMENT_PACK_SELECT_INDEX) into a pack expansion.
+ In this case, the Ith element resulting from this
+ substituting is going to be a pack expansion, which
+ pattern is the pattern of E. Let's return the
+ pattern of E, and
+ gen_elem_of_pack_expansion_instantiation will
+ build the resulting pack expansion from it. */
+ if (PACK_EXPANSION_P (arg))
+ arg = PACK_EXPANSION_PATTERN (arg);
+ }
}
if (arg == error_mark_node)
new file mode 100644
@@ -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;
new file mode 100644
@@ -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, "");
new file mode 100644
@@ -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, "");