PR c++/89761 - ICE with sizeof... in pack expansion.

In this testcase we get confused when looking at the sizeof... because the
argument pack for 'args' has been wrapped in an ARGUMENT_PACK_SELECT as part
of expanding the fold-expression.  We handle this situation a bit lower down
in tsubst_pack_expansion, but that doesn't help the call to
argument_pack_element_is_expansion_p, which happens earlier.

	* pt.c (argument_pack_element_is_expansion_p): Handle
	ARGUMENT_PACK_SELECT.

From-SVN: r269776

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a3341bd96726b6df6393636ecaedcb5b674ea681..d4dc5d7146aa77f14b2c300768bdfa2d191201db 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,9 @@
 2019-03-18  Jason Merrill  <jason@redhat.com>
 
+       PR c++/89761 - ICE with sizeof... in pack expansion.
+       * pt.c (argument_pack_element_is_expansion_p): Handle
+       ARGUMENT_PACK_SELECT.
+
        PR c++/89640 - GNU attributes on lambda.
        * parser.c (cp_parser_lambda_declarator_opt): Allow GNU attributes.
 

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 7dc6e44cf7be99999ce1c6fec7592b23f98b99a9..0acc16d1b92294cd5e58d91303b2584f69270d9a 100644 (file)
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -11544,6 +11544,9 @@ make_fnparm_pack (tree spec_parm)
 static int
 argument_pack_element_is_expansion_p (tree arg_pack, int i)
 {
+  if (TREE_CODE (arg_pack) == ARGUMENT_PACK_SELECT)
+    /* We're being called before this happens in tsubst_pack_expansion.  */
+    arg_pack = ARGUMENT_PACK_SELECT_FROM_PACK (arg_pack);
   tree vec = ARGUMENT_PACK_ARGS (arg_pack);
   if (i >= TREE_VEC_LENGTH (vec))
     return 0;

diff --git a/gcc/testsuite/g++.dg/cpp1z/fold10.C b/gcc/testsuite/g++.dg/cpp1z/fold10.C
new file mode 100644 (file)
index 0000000..1bd39a0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/fold10.C
@@ -0,0 +1,17 @@
+// PR c++/89761
+// { dg-do compile { target c++17 } }
+
+template <int...> struct seq {};
+template <bool> struct S {
+    template <typename Args>
+    constexpr static void call(Args&&...) {}
+};
+
+template <int ...Idx,typename ...Args>
+auto foo (seq<Idx...>, Args&& ...args) {
+    return (S<Idx==sizeof...(args)>::call(args), ...);
+}
+
+void bar() {
+    foo(seq<0,1,2>{}, 1,2,3);
+}