Here sizeof... was improperly being resolved early on an argument pack
consisting of a single pack expansion, when the sizeof... is still
dependent. This turned out to be because of our handling of partial
instantiation of a function parameter pack: I had previously changed
extract_fnparm_pack to wrap such a partially instantiated pack in an
EXPR_PACK_EXPANSION, but later reverted that because it was breaking
things. That breakage turns out to have been because the uses of
ARGUMENT_PACK_EXTRACT_ARG for PARM_DECL and VAR_DECL were missing the
code to strip a pack expansion that we had for template parameters;
moving all of that into a function rather than a macro fixed that, and
so now we can wrap the parameter pack again, which fixes the testcase.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 0978de34113258d973e3a78dad466c3d602a9130
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Feb 12 17:04:56 2018 -0500
PR c++/84338 - wrong variadic sizeof.
* pt.c (argument_pack_select_arg): Like the macro, but look through
a pack expansion.
(tsubst, tsubst_copy, dependent_template_arg_p): Use it.
(extract_fnparm_pack): Do make_pack_expansion.
(extract_locals_r): Do strip a pack expansion.
* cp-tree.h (ARGUMENT_PACK_SELECT_ARG): Remove.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index a6c75aed33d..9a9e9f0bbcb 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -3558,12 +3558,6 @@ extern void decl_shadowed_for_var_insert (tree, tree);
#define ARGUMENT_PACK_SELECT_INDEX(NODE) \
(((struct tree_argument_pack_select *)ARGUMENT_PACK_SELECT_CHECK
(NODE))->index)
-/* In an ARGUMENT_PACK_SELECT, the actual underlying argument that the
- ARGUMENT_PACK_SELECT represents. */
-#define ARGUMENT_PACK_SELECT_ARG(NODE) \
- TREE_VEC_ELT (ARGUMENT_PACK_ARGS (ARGUMENT_PACK_SELECT_FROM_PACK (NODE)), \
- ARGUMENT_PACK_SELECT_INDEX (NODE))
-
#define FOLD_EXPR_CHECK(NODE) \
TREE_CHECK4 (NODE, UNARY_LEFT_FOLD_EXPR, UNARY_RIGHT_FOLD_EXPR, \
BINARY_LEFT_FOLD_EXPR, BINARY_RIGHT_FOLD_EXPR)
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index b58c60f0dcb..a83b7073d20 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -3394,6 +3394,34 @@ get_template_argument_pack_elems (const_tree t)
return ARGUMENT_PACK_ARGS (t);
}
+/* In an ARGUMENT_PACK_SELECT, the actual underlying argument that the
+ ARGUMENT_PACK_SELECT represents. */
+
+static tree
+argument_pack_select_arg (tree t)
+{
+ tree args = ARGUMENT_PACK_ARGS (ARGUMENT_PACK_SELECT_FROM_PACK (t));
+ tree arg = TREE_VEC_ELT (args, ARGUMENT_PACK_SELECT_INDEX (t));
+
+ /* 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 an argument pack (of which the 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))
+ {
+ /* Make sure we aren't throwing away arg info. */
+ gcc_assert (!PACK_EXPANSION_EXTRA_ARGS (arg));
+ arg = PACK_EXPANSION_PATTERN (arg);
+ }
+
+ return arg;
+}
+
+
/* True iff FN is a function representing a built-in variadic parameter
pack. */
@@ -10933,7 +10961,12 @@ extract_fnparm_pack (tree tmpl_parm, tree *spec_p)
parmvec = make_tree_vec (len);
spec_parm = *spec_p;
for (i = 0; i < len; i++, spec_parm = DECL_CHAIN (spec_parm))
- TREE_VEC_ELT (parmvec, i) = spec_parm;
+ {
+ tree elt = spec_parm;
+ if (DECL_PACK_P (elt))
+ elt = make_pack_expansion (elt);
+ TREE_VEC_ELT (parmvec, i) = elt;
+ }
/* Build the argument packs. */
SET_ARGUMENT_PACK_ARGS (argpack, parmvec);
@@ -11388,7 +11421,8 @@ extract_locals_r (tree *tp, int */*walk_subtrees*/,
void *data)
/* Pull out the actual PARM_DECL for the partial instantiation. */
tree args = ARGUMENT_PACK_ARGS (spec);
gcc_assert (TREE_VEC_LENGTH (args) == 1);
- spec = TREE_VEC_ELT (args, 0);
+ tree arg = TREE_VEC_ELT (args, 0);
+ spec = PACK_EXPANSION_PATTERN (arg);
}
*extra = tree_cons (*tp, spec, *extra);
}
@@ -13747,29 +13781,9 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
{
arg = TMPL_ARG (args, level, idx);
+ /* See through ARGUMENT_PACK_SELECT arguments. */
if (arg && TREE_CODE (arg) == ARGUMENT_PACK_SELECT)
- {
- /* 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))
- {
- /* Make sure we aren't throwing away arg info. */
- gcc_assert (!PACK_EXPANSION_EXTRA_ARGS (arg));
- arg = PACK_EXPANSION_PATTERN (arg);
- }
- }
+ arg = argument_pack_select_arg (arg);
}
if (arg == error_mark_node)
@@ -14734,7 +14748,7 @@ tsubst_copy (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
}
if (TREE_CODE (r) == ARGUMENT_PACK_SELECT)
- r = ARGUMENT_PACK_SELECT_ARG (r);
+ r = argument_pack_select_arg (r);
if (!mark_used (r, complain) && !(complain & tf_error))
return error_mark_node;
return r;
@@ -14866,7 +14880,7 @@ tsubst_copy (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
register_local_specialization (r, t);
}
if (TREE_CODE (r) == ARGUMENT_PACK_SELECT)
- r = ARGUMENT_PACK_SELECT_ARG (r);
+ r = argument_pack_select_arg (r);
}
else
r = t;
@@ -24701,7 +24715,7 @@ dependent_template_arg_p (tree arg)
return true;
if (TREE_CODE (arg) == ARGUMENT_PACK_SELECT)
- arg = ARGUMENT_PACK_SELECT_ARG (arg);
+ arg = argument_pack_select_arg (arg);
if (TREE_CODE (arg) == TEMPLATE_TEMPLATE_PARM)
return true;
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic13.C
b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic13.C
new file mode 100644
index 00000000000..92fd34cb268
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic13.C
@@ -0,0 +1,15 @@
+// PR c++/84338
+// { dg-do compile { target c++14 } }
+
+template < typename ... T >
+auto f(T ... i){
+ [](auto ... i){
+ // // wrongly true in current trunk
+ // static_assert(sizeof...(i) == 1, "");
+ static_assert(sizeof...(i) == 2, "");
+ }(i ...);
+}
+
+int main(){
+ f(0, 1);
+}
