PR c++/82249 - wrong mismatched pack length error.

	* pt.c (extract_fnparm_pack, tsubst_pack_expansion): Handle
	unsubstituted function parameter pack.

From-SVN: r257018

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index bc89041a7daa612a3f24ec775264bab178cfaf1a..2c499dbc323f7460016be4676621017919d06c54 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-23  Jason Merrill  <jason@redhat.com>
+
+       PR c++/82249 - wrong mismatched pack length error.
+       * pt.c (extract_fnparm_pack, tsubst_pack_expansion): Handle
+       unsubstituted function parameter pack.
+
 2018-01-23  Paolo Carlini  <paolo.carlini@oracle.com>
 
        PR c++/83921

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index d39b54ed408d8ad3a4e7e276c9d7c77042a8d36a..abfdbd96ae8d0494033432f9b58c342200884a27 100644 (file)
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -10961,7 +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);
@@ -11414,6 +11419,7 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
   tree pattern;
   tree pack, packs = NULL_TREE;
   bool unsubstituted_packs = false;
+  bool unsubstituted_fn_pack = false;
   int i, len = -1;
   tree result;
   hash_map<tree, tree> *saved_local_specializations = NULL;
@@ -11484,6 +11490,13 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
              else
                arg_pack = make_fnparm_pack (arg_pack);
            }
+         else if (argument_pack_element_is_expansion_p (arg_pack, 0))
+           /* This argument pack isn't fully instantiated yet.  We set this
+              flag rather than clear arg_pack because we do want to do the
+              optimization below, and we don't want to substitute directly
+              into the pattern (as that would expose a NONTYPE_ARGUMENT_PACK
+              where it isn't expected).  */
+           unsubstituted_fn_pack = true;
        }
       else if (TREE_CODE (parm_pack) == FIELD_DECL)
        arg_pack = tsubst_copy (parm_pack, args, complain, in_decl);
@@ -11521,7 +11534,8 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
 
           if (len < 0)
            len = my_len;
-          else if (len != my_len)
+          else if (len != my_len
+                  && !unsubstituted_fn_pack)
             {
              if (!(complain & tf_error))
                /* Fail quietly.  */;
@@ -11574,7 +11588,8 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
 
   /* We cannot expand this expansion expression, because we don't have
      all of the argument packs we need.  */
-  if (use_pack_expansion_extra_args_p (packs, len, unsubstituted_packs))
+  if (use_pack_expansion_extra_args_p (packs, len, (unsubstituted_packs
+                                                   || unsubstituted_fn_pack)))
     {
       /* We got some full packs, but we can't substitute them in until we
         have values for all the packs.  So remember these until then.  */

diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic7.C b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic7.C
new file mode 100644 (file)
index 0000000..5c5af14
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic7.C
@@ -0,0 +1,19 @@
+// PR c++/82249
+// { dg-do compile { target c++14 } }
+
+template<class T, class U> T calc (T t, U u) { return t; }
+template <class... Ts> void sink(Ts...);
+
+template < typename ... Ds >
+void f(Ds ...) {
+  [](auto ... n){
+    sink (calc(n, Ds{}) ...);
+  }(Ds{} ...);
+}
+
+
+int main(){
+  f();      // Wrong error
+  f(0, 0);  // Wrong error
+  f(0);     // ICE
+}