When substituting into the arguments of a base initializer pack
expansion, tsubst_initializer_list uses a dummy EXPR_PACK_EXPANSION
in order to expand an initializer such as Bases(args)... into
Bases#{0}(args#{0}) and so on. But when an argument inside the base
initializer is itself an pack expansion, e.g. in Bases(args...)..., the
argument is already an EXPR_PACK_EXPANSION so we don't need to wrap it,
it's also is independent from the outer one for Bases, so we need to
multiplicatively append all expanded arguments onto the argument list
for each expanded base.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?
gcc/cp/ChangeLog:
PR c++/88580
* pt.c (tsubst_initializer_list): Correctly handle the case
where an argument inside a base initializer pack expansion is
itself a pack expansion.
gcc/testsuite/ChangeLog:
PR c++/88580
* g++.dg/cpp0x/variadic182.C: New test.
---
gcc/cp/pt.c | 28 +++++++++++++++++-------
gcc/testsuite/g++.dg/cpp0x/variadic182.C | 18 +++++++++++++++
2 files changed, 38 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic182.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 8c3c814ce55..eaf46659f85 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -26389,9 +26389,16 @@ tsubst_initializer_list (tree t, tree argvec)
tree expanded_exprs;
/* Expand the argument. */
- SET_PACK_EXPANSION_PATTERN (expr, TREE_VALUE (arg));
+ tree value;
+ if (TREE_CODE (TREE_VALUE (arg)) == EXPR_PACK_EXPANSION)
+ value = TREE_VALUE (arg);
+ else
+ {
+ value = expr;
+ SET_PACK_EXPANSION_PATTERN (value, TREE_VALUE (arg));
+ }
expanded_exprs
- = tsubst_pack_expansion (expr, argvec,
+ = tsubst_pack_expansion (value, argvec,
tf_warning_or_error,
NULL_TREE);
if (expanded_exprs == error_mark_node)
@@ -26400,12 +26407,17 @@ tsubst_initializer_list (tree t, tree argvec)
/* Prepend each of the expanded expressions to the
corresponding TREE_LIST in EXPANDED_ARGUMENTS. */
for (i = 0; i < len; i++)
- {
- TREE_VEC_ELT (expanded_arguments, i) =
- tree_cons (NULL_TREE,
- TREE_VEC_ELT (expanded_exprs, i),
- TREE_VEC_ELT (expanded_arguments, i));
- }
+ if (TREE_CODE (TREE_VALUE (arg)) == EXPR_PACK_EXPANSION)
+ for (int j = 0; j < TREE_VEC_LENGTH (expanded_exprs); j++)
+ TREE_VEC_ELT (expanded_arguments, i)
+ = tree_cons (NULL_TREE,
+ TREE_VEC_ELT (expanded_exprs, j),
+ TREE_VEC_ELT (expanded_arguments, i));
+ else
+ TREE_VEC_ELT (expanded_arguments, i)
+ = tree_cons (NULL_TREE,
+ TREE_VEC_ELT (expanded_exprs, i),
+ TREE_VEC_ELT (expanded_arguments, i));
}
in_base_initializer = 0;
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic182.C
b/gcc/testsuite/g++.dg/cpp0x/variadic182.C
new file mode 100644
index 00000000000..078de740e01
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic182.C
@@ -0,0 +1,18 @@
+// PR c++/88580
+// { dg-do compile { target c++11 } }
+
+template <class... Bases>
+struct Derived : Bases... {
+ template <class... Ts>
+ Derived(Ts... args) : Bases(args, args..., args)... { }
+};
+
+struct A { };
+struct B { };
+struct C { };
+
+struct Base1 { Base1(A, A, B, C, A); };
+struct Base2 { Base2(B, A, B, C, B); };
+struct Base3 { Base3(C, A, B, C, C); };
+
+Derived<Base1, Base2, Base3> d(A{}, B{}, C{});
--
2.31.1.362.g311531c9de
