Here, the problem was that when we substitute into a parameter pack
PARM_DECL to get a dummy decl for use in a decltype context, we were
continuing to tsubst into its DECL_CHAIN as well, which causes problems
if a following parameter uses the previous parameter, as in this testcase.
In tsubst_copy we've dealt with this issue for non-pack parameters by
doing a copy_node before calling tsubst_decl, but it occurred to me that
we could check cp_unevaluated_context instead to avoid the extra allocation.
Tested x86_64-pc-linux-gnu, applying to trunk. Alternative patch that
just does the copy for packs as well tested and applying to 4.7.
commit 9b1909cf6cf54f405b83e312483d263d9c4b6f92
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Jun 25 17:02:48 2012 -0400
PR c++/53498
PR c++/53305
* pt.c (tsubst_decl) [PARM_DECL]: Don't recurse into DECL_CHAIN
if cp_unevaluated_operand is set.
(tsubst_copy) [PARM_DECL]: Don't copy before tsubsting.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index ad7134b..7e1c46f 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -10497,7 +10497,9 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain)
DECL_CHAIN (prev_r) = r;
}
- if (DECL_CHAIN (t))
+ /* If cp_unevaluated_operand is set, we're just looking for a
+ single dummy parameter, so don't keep going. */
+ if (DECL_CHAIN (t) && !cp_unevaluated_operand)
DECL_CHAIN (r) = tsubst (DECL_CHAIN (t), args,
complain, DECL_CHAIN (t));
@@ -12078,8 +12080,6 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
if (r == NULL_TREE)
{
- tree c;
-
/* We get here for a use of 'this' in an NSDMI. */
if (DECL_NAME (t) == this_identifier
&& at_function_scope_p ()
@@ -12090,12 +12090,7 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
declaration (such as in a late-specified return type). Just
make a dummy decl, since it's only used for its type. */
gcc_assert (cp_unevaluated_operand != 0);
- /* We copy T because want to tsubst the PARM_DECL only,
- not the following PARM_DECLs that are chained to T. */
- c = copy_node (t);
- r = tsubst_decl (c, args, complain);
- if (r == NULL_TREE)
- return error_mark_node;
+ r = tsubst_decl (t, args, complain);
/* Give it the template pattern as its context; its true context
hasn't been instantiated yet and this is good enough for
mangling. */
diff --git a/gcc/testsuite/g++.dg/cpp0x/decltype38.C b/gcc/testsuite/g++.dg/cpp0x/decltype38.C
new file mode 100644
index 0000000..97ebb33
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/decltype38.C
@@ -0,0 +1,17 @@
+// PR c++/53498
+// { dg-do compile { target c++11 } }
+
+template<typename... Args>
+struct B
+{
+ template<typename U>
+ static
+ void b(const U& u, const Args&... args,
+ decltype(u.f(args...)) dummy)
+ {
+ }
+};
+
+int main() {
+ B<int> b;
+}
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic132.C b/gcc/testsuite/g++.dg/cpp0x/variadic132.C
index f50c7a6..1b9c286 100644
--- a/gcc/testsuite/g++.dg/cpp0x/variadic132.C
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic132.C
@@ -9,11 +9,11 @@ struct funct
int operator()(argTs...);
};
-template<class...> class test;
+template<class...> struct test;
template<template <class...> class tp,
class... arg1Ts, class... arg2Ts>
-class test<tp<arg1Ts...>, tp<arg2Ts...>>
+struct test<tp<arg1Ts...>, tp<arg2Ts...>>
{
template<class func, class...arg3Ts>
auto test2(func fun, arg1Ts... arg1s, arg3Ts... arg3s)
@@ -23,5 +23,5 @@ class test<tp<arg1Ts...>, tp<arg2Ts...>>
int main()
{
test<tuple<>, tuple<char,int>> t2;
- t2.test2(funct(), 'a', 2); // { dg-error "no matching function" }
+ t2.test2(funct(), 'a', 2);
}
commit 1965f161a59d81a408cd2369e7a393fa17e95ede
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Jun 25 17:32:32 2012 -0400
PR c++/53498
PR c++/53305
* pt.c (tsubst_pack_expansion): Copy before dummy tsubst.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 7f5682d..1b5ab9e 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -9393,7 +9393,9 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
late-specified return type). Even if it exists, it might
have the wrong value for a recursive call. Just make a
dummy decl, since it's only used for its type. */
- arg_pack = tsubst_decl (parm_pack, args, complain);
+ /* Copy before tsubsting so that we don't recurse into any
+ later PARM_DECLs. */
+ arg_pack = tsubst_decl (copy_node (parm_pack), args, complain);
if (arg_pack && FUNCTION_PARAMETER_PACK_P (arg_pack))
/* Partial instantiation of the parm_pack, we can't build
up an argument pack yet. */
diff --git a/gcc/testsuite/g++.dg/cpp0x/decltype38.C b/gcc/testsuite/g++.dg/cpp0x/decltype38.C
new file mode 100644
index 0000000..97ebb33
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/decltype38.C
@@ -0,0 +1,17 @@
+// PR c++/53498
+// { dg-do compile { target c++11 } }
+
+template<typename... Args>
+struct B
+{
+ template<typename U>
+ static
+ void b(const U& u, const Args&... args,
+ decltype(u.f(args...)) dummy)
+ {
+ }
+};
+
+int main() {
+ B<int> b;
+}
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic132.C b/gcc/testsuite/g++.dg/cpp0x/variadic132.C
new file mode 100644
index 0000000..1b9c286
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic132.C
@@ -0,0 +1,27 @@
+// PR c++/53305
+// { dg-do compile { target c++11 } }
+
+template<class... Ts> struct tuple { };
+
+struct funct
+{
+ template<class... argTs>
+ int operator()(argTs...);
+};
+
+template<class...> struct test;
+
+template<template <class...> class tp,
+ class... arg1Ts, class... arg2Ts>
+struct test<tp<arg1Ts...>, tp<arg2Ts...>>
+{
+ template<class func, class...arg3Ts>
+ auto test2(func fun, arg1Ts... arg1s, arg3Ts... arg3s)
+ -> decltype(fun(arg1s..., arg3s...));
+};
+
+int main()
+{
+ test<tuple<>, tuple<char,int>> t2;
+ t2.test2(funct(), 'a', 2);
+}
