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re PR c++/46394 ([C++0X] [4.6 Regression] no matching function with default template parameter)

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PR c++/46394

gcc/cp/

	PR c++/46394
	* pt.c (tsubst_pack_expansion): do not use
	cp_tree_equal/same_type_p to detect an expansion of a parameter
	pack.

gcc/testsuite/

	PR c++/46394
	* g++.dg/template/typedef38.C: New test.

From-SVN: r170341
This commit is contained in:
Dodji Seketeli 2011-02-20 17:37:03 +00:00 • committed by Dodji Seketeli
parent 67ad6c8252
commit 869b0af5c5
4 changed files with 78 additions and 7 deletions
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7
gcc/cp/ChangeLog
View file

@ -1,3 +1,10 @@
2011-02-20 Dodji Seketeli <dodji@redhat.com>
PR c++/46394
* pt.c (tsubst_pack_expansion): do not use
cp_tree_equal/same_type_p to detect an expansion of a parameter
pack.
2011-02-19 Jason Merrill <jason@redhat.com>
PR c++/47503

46
gcc/cp/pt.c
View file

@ -8711,19 +8711,51 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
return result;
}
/* 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. */
/* So we have an argument_pack<P...>. We want to test if P
is actually PARM_PACK. We will not use cp_tree_equal to
test P and PARM_PACK because during type fixup (by
fixup_template_parm) P can be a pre-fixup version of a
type and PARM_PACK be its post-fixup version.
cp_tree_equal would consider them as different even
though we would want to consider them compatible for our
precise purpose here.
Thus we are going to consider that P and PARM_PACK are
compatible if they have the same DECL. */
if ((/* If ARG_PACK is a type parameter pack named by the
same DECL as parm_pack ... */
(TYPE_P (pattern)
&& TYPE_P (parm_pack)
&& TYPE_NAME (pattern) == TYPE_NAME (parm_pack))
/* ... or if ARG_PACK is a non-type parameter
named by the same DECL as parm_pack ... */
|| (TREE_CODE (pattern) == TEMPLATE_PARM_INDEX
&& TREE_CODE (parm_pack) == PARM_DECL
&& TEMPLATE_PARM_DECL (pattern)
== TEMPLATE_PARM_DECL (DECL_INITIAL (parm_pack))))
&& template_parameter_pack_p (pattern))
/* ... then 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;
}

5
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,8 @@
2011-02-20 Dodji Seketeli <dodji@redhat.com>
PR c++/46394
* g++.dg/template/typedef38.C: New test.
2011-02-20 Paul Thomas <pault@gcc.gnu.org>
PR fortran/46818

27
gcc/testsuite/g++.dg/template/typedef38.C Normal file
View file

@ -0,0 +1,27 @@
// Origin: PR c++/46394
// { dg-options "-std=c++0x" }
// { dg-do "compile" }
template<class T>
struct S0
{
typedef T type;
};
template<class... X>
struct S1
{
typedef int I;
};
struct A
{
template<class...U, class V=typename S1<typename S0<U>::type...>::I>
A(U...u);
};
int
main()
{
A a(1, 2);
}