c++/48320 - Template parameter packs cannot be expanded in default template arguments
gcc/cp/ PR c++/48320 * pt.c (template_parameter_pack_p): Support TEMPLATE_PARM_INDEX nodes. Add a comment. (arg_from_parm_pack_p): New static function, factorized out from tsubst_pack_expansion and extended to support non-type parameter packs represented with TEMPLATE_PARM_INDEX nodes. (tsubst_pack_expansion): Use arg_from_parm_pack_p. gcc/testsuite/ PR c++/48320 * g++.dg/cpp0x/variadic116.C: New test case. From-SVN: r178811
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Dodji Seketeli
Dodji Seketeli
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1f15c50b16
@ -1,3 +1,13 @@
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2011-09-13 Dodji Seketeli <dodji@redhat.com>
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PR c++/48320
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* pt.c (template_parameter_pack_p): Support TEMPLATE_PARM_INDEX
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nodes. Add a comment.
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(arg_from_parm_pack_p): New static function, factorized out from
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tsubst_pack_expansion and extended to support non-type parameter
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packs represented with TEMPLATE_PARM_INDEX nodes.
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(tsubst_pack_expansion): Use arg_from_parm_pack_p.
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2011-09-12 Jason Merrill <jason@redhat.com>
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* pt.c (type_unification_real): Fix handling of DEDUCE_CONV
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115
gcc/cp/pt.c
115
gcc/cp/pt.c
@ -203,6 +203,7 @@ static void append_type_to_template_for_access_check_1 (tree, tree, tree,
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static tree listify (tree);
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static tree listify_autos (tree, tree);
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static tree template_parm_to_arg (tree t);
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static bool arg_from_parm_pack_p (tree, tree);
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static tree current_template_args (void);
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static tree fixup_template_type_parm_type (tree, int);
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static tree fixup_template_parm_index (tree, tree, int);
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@ -2741,12 +2742,15 @@ template_parameter_pack_p (const_tree parm)
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if (TREE_CODE (parm) == PARM_DECL)
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return (DECL_TEMPLATE_PARM_P (parm)
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&& TEMPLATE_PARM_PARAMETER_PACK (DECL_INITIAL (parm)));
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if (TREE_CODE (parm) == TEMPLATE_PARM_INDEX)
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return TEMPLATE_PARM_PARAMETER_PACK (parm);
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/* If this is a list of template parameters, we could get a
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TYPE_DECL or a TEMPLATE_DECL. */
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if (TREE_CODE (parm) == TYPE_DECL || TREE_CODE (parm) == TEMPLATE_DECL)
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parm = TREE_TYPE (parm);
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/* Otherwise it must be a type template parameter. */
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return ((TREE_CODE (parm) == TEMPLATE_TYPE_PARM
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|| TREE_CODE (parm) == TEMPLATE_TEMPLATE_PARM)
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&& TEMPLATE_TYPE_PARAMETER_PACK (parm));
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@ -4005,6 +4009,63 @@ template_parm_to_arg (tree t)
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return t;
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}
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/* This function returns TRUE if PARM_PACK is a template parameter
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pack and if ARG_PACK is what template_parm_to_arg returned when
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passed PARM_PACK. */
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static bool
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arg_from_parm_pack_p (tree arg_pack, tree parm_pack)
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{
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/* For clarity in the comments below let's use the representation
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argument_pack<elements>' to denote an argument pack and its
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elements.
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In the 'if' block below, we want to detect cases where
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ARG_PACK is argument_pack<PARM_PACK...>. I.e, we want to
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check if ARG_PACK is an argument pack which sole element is
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the expansion of PARM_PACK. That argument pack is typically
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created by template_parm_to_arg when passed a parameter
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pack. */
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if (arg_pack
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&& TREE_VEC_LENGTH (ARGUMENT_PACK_ARGS (arg_pack)) == 1
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&& PACK_EXPANSION_P (TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack), 0)))
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{
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tree expansion = TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack), 0);
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tree pattern = PACK_EXPANSION_PATTERN (expansion);
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/* So we have an argument_pack<P...>. We want to test if P
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is actually PARM_PACK. We will not use cp_tree_equal to
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test P and PARM_PACK because during type fixup (by
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fixup_template_parm) P can be a pre-fixup version of a
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type and PARM_PACK be its post-fixup version.
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cp_tree_equal would consider them as different even
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though we would want to consider them compatible for our
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precise purpose here.
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Thus we are going to consider that P and PARM_PACK are
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compatible if they have the same DECL. */
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if ((/* If ARG_PACK is a type parameter pack named by the
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same DECL as parm_pack ... */
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(TYPE_P (pattern)
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&& TYPE_P (parm_pack)
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&& TYPE_NAME (pattern) == TYPE_NAME (parm_pack))
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/* ... or if PARM_PACK is a non-type parameter named by the
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same DECL as ARG_PACK. Note that PARM_PACK being a
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non-type parameter means it's either a PARM_DECL or a
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TEMPLATE_PARM_INDEX. */
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|| (TREE_CODE (pattern) == TEMPLATE_PARM_INDEX
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&& ((TREE_CODE (parm_pack) == PARM_DECL
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&& (TEMPLATE_PARM_DECL (pattern)
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== TEMPLATE_PARM_DECL (DECL_INITIAL (parm_pack))))
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|| (TREE_CODE (parm_pack) == TEMPLATE_PARM_INDEX
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&& (TEMPLATE_PARM_DECL (pattern)
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== TEMPLATE_PARM_DECL (parm_pack))))))
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&& template_parameter_pack_p (pattern))
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return true;
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}
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return false;
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}
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/* Within the declaration of a template, return all levels of template
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parameters that apply. The template parameters are represented as
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a TREE_VEC, in the form documented in cp-tree.h for template
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@ -9105,53 +9166,13 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
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return result;
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}
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/* For clarity in the comments below let's use the
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representation 'argument_pack<elements>' to denote an
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argument pack and its elements.
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In the 'if' block below, we want to detect cases where
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ARG_PACK is argument_pack<PARM_PACK...>. I.e, we want to
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check if ARG_PACK is an argument pack which sole element is
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the expansion of PARM_PACK. That argument pack is typically
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created by template_parm_to_arg when passed a parameter
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pack. */
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if (arg_pack
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&& TREE_VEC_LENGTH (ARGUMENT_PACK_ARGS (arg_pack)) == 1
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&& PACK_EXPANSION_P (TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack), 0)))
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{
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tree expansion = TREE_VEC_ELT (ARGUMENT_PACK_ARGS (arg_pack), 0);
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tree pattern = PACK_EXPANSION_PATTERN (expansion);
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/* So we have an argument_pack<P...>. We want to test if P
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is actually PARM_PACK. We will not use cp_tree_equal to
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test P and PARM_PACK because during type fixup (by
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fixup_template_parm) P can be a pre-fixup version of a
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type and PARM_PACK be its post-fixup version.
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cp_tree_equal would consider them as different even
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though we would want to consider them compatible for our
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precise purpose here.
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Thus we are going to consider that P and PARM_PACK are
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compatible if they have the same DECL. */
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if ((/* If ARG_PACK is a type parameter pack named by the
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same DECL as parm_pack ... */
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(TYPE_P (pattern)
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&& TYPE_P (parm_pack)
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&& TYPE_NAME (pattern) == TYPE_NAME (parm_pack))
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/* ... or if ARG_PACK is a non-type parameter
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named by the same DECL as parm_pack ... */
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|| (TREE_CODE (pattern) == TEMPLATE_PARM_INDEX
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&& TREE_CODE (parm_pack) == PARM_DECL
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&& TEMPLATE_PARM_DECL (pattern)
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== TEMPLATE_PARM_DECL (DECL_INITIAL (parm_pack))))
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&& template_parameter_pack_p (pattern))
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/* ... then the argument pack that the parameter maps to
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is just an expansion of the parameter itself, such as
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one would find in the implicit typedef of a class
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inside the class itself. Consider this parameter
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"unsubstituted", so that we will maintain the outer
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pack expansion. */
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arg_pack = NULL_TREE;
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}
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if (arg_from_parm_pack_p (arg_pack, parm_pack))
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/* The argument pack that the parameter maps to is just an
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expansion of the parameter itself, such as one would find
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in the implicit typedef of a class inside the class itself.
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Consider this parameter "unsubstituted", so that we will
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maintain the outer pack expansion. */
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arg_pack = NULL_TREE;
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if (arg_pack)
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{
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@ -1,3 +1,8 @@
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2011-09-13 Dodji Seketeli <dodji@redhat.com>
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PR c++/48320
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* g++.dg/cpp0x/variadic116.C: New test case.
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2011-09-12 Richard Sandiford <rdsandiford@googlemail.com>
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* gcc.target/mips/mips.exp (mips_option_groups): Add debug options.
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32
gcc/testsuite/g++.dg/cpp0x/variadic116.C
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32
gcc/testsuite/g++.dg/cpp0x/variadic116.C
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@ -0,0 +1,32 @@
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// Origin: PR c++/48320
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// { dg-options -std=c++0x }
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template<class... T>
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struct tuple
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{
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typedef int type;
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};
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template<int... Indices>
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struct indices
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{
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};
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template<unsigned i, class Tuple>
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struct tuple_element
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{
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typedef Tuple type;
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};
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template<class Tuple,
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int... Indices,
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class Result = tuple<typename tuple_element<Indices, Tuple>::type...> >
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Result
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f(Tuple&&, indices<Indices...>);
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void
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foo()
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{
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f(tuple<int, char, unsigned> (), indices<2, 1, 0> ());
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}
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