re PR c++/81957 (ICE decltype)

/cp
2017-11-02  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/81957
	* pt.c (make_pack_expansion): Add tsubst_flags_t parameter.
	(expand_integer_pack, convert_template_argument, coerce_template_parms,
	gen_elem_of_pack_expansion_instantiation, tsubst_pack_expansion,
	unify): Adjust calls.
	* tree.c (cp_build_qualified_type_real): Likewise.
	* cp-tree.h (make_pack_expansion): Adjust declaration.

/testsuite
2017-11-02  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/81957
	* g++.dg/cpp0x/variadic-crash5.C: New.

From-SVN: r254361

gcc/cp/ChangeLog

+2017-11-02  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/81957
+	* pt.c (make_pack_expansion): Add tsubst_flags_t parameter.
+	(expand_integer_pack, convert_template_argument, coerce_template_parms,
+	gen_elem_of_pack_expansion_instantiation, tsubst_pack_expansion,
+	unify): Adjust calls.
+	* tree.c (cp_build_qualified_type_real): Likewise.
+	* cp-tree.h (make_pack_expansion): Adjust declaration.
+
 2017-11-02  Nathan Sidwell  <nathan@acm.org>
 
 	* cp-tree.h (IDENTIFIER_NEWDEL_OP_P): Restore, adjust.

gcc/cp/cp-tree.h

@@ -6482,7 +6482,7 @@ extern bool uses_parameter_packs                (tree);
 extern bool template_parameter_pack_p           (const_tree);
 extern bool function_parameter_pack_p		(const_tree);
 extern bool function_parameter_expanded_from_pack_p (tree, tree);
-extern tree make_pack_expansion                 (tree);
+extern tree make_pack_expansion                 (tree, tsubst_flags_t = tf_warning_or_error);
 extern bool check_for_bare_parameter_packs      (tree);
 extern tree build_template_info			(tree, tree);
 extern tree get_template_info			(const_tree);

gcc/cp/pt.c

@@ -3435,7 +3435,7 @@ expand_integer_pack (tree call, tree args, tsubst_flags_t complain,
 	  call = copy_node (call);
 	  CALL_EXPR_ARG (call, 0) = hi;
 	}
-      tree ex = make_pack_expansion (call);
+      tree ex = make_pack_expansion (call, complain);
       tree vec = make_tree_vec (1);
       TREE_VEC_ELT (vec, 0) = ex;
       return vec;
@@ -3724,7 +3724,7 @@ uses_parameter_packs (tree t)
    EXPR_PACK_EXPANSION, TYPE_PACK_EXPANSION, or TREE_LIST,
    respectively.  */
 tree 
-make_pack_expansion (tree arg)
+make_pack_expansion (tree arg, tsubst_flags_t complain)
 {
   tree result;
   tree parameter_packs = NULL_TREE;
@@ -3770,7 +3770,9 @@ make_pack_expansion (tree arg)
 
       if (parameter_packs == NULL_TREE)
         {
-          error ("base initializer expansion %qT contains no parameter packs", arg);
+	  if (complain & tf_error)
+	    error ("base initializer expansion %qT contains no parameter packs",
+		   arg);
           delete ppd.visited;
           return error_mark_node;
         }
@@ -3834,10 +3836,13 @@ make_pack_expansion (tree arg)
   /* Make sure we found some parameter packs.  */
   if (parameter_packs == NULL_TREE)
     {
+      if (complain & tf_error)
+	{
 	  if (TYPE_P (arg))
 	    error ("expansion pattern %qT contains no argument packs", arg);
 	  else
 	    error ("expansion pattern %qE contains no argument packs", arg);
+	}
       return error_mark_node;
     }
   PACK_EXPANSION_PARAMETER_PACKS (result) = parameter_packs;
@@ -7694,7 +7699,7 @@ convert_template_argument (tree parm,
                       if (DECL_TEMPLATE_TEMPLATE_PARM_P (val))
                         val = TREE_TYPE (val);
 		      if (TREE_CODE (orig_arg) == TYPE_PACK_EXPANSION)
-			val = make_pack_expansion (val);
+			val = make_pack_expansion (val, complain);
                     }
 		}
 	      else
@@ -8188,7 +8193,7 @@ coerce_template_parms (tree parms,
 	      else if (TYPE_P (conv) && !TYPE_P (pattern))
 		/* Recover from missing typename.  */
 		TREE_VEC_ELT (inner_args, arg_idx)
-		  = make_pack_expansion (conv);
+		  = make_pack_expansion (conv, complain);
 
               /* We don't know how many args we have yet, just
                  use the unconverted ones for now.  */
@@ -11161,7 +11166,7 @@ gen_elem_of_pack_expansion_instantiation (tree pattern,
       the Ith element resulting from the substituting is going to
       be a pack expansion as well.  */
   if (ith_elem_is_expansion)
-    t = make_pack_expansion (t);
+    t = make_pack_expansion (t, complain);
 
   return t;
 }
@@ -11573,7 +11578,7 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
       /* 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.  */
 
-      t = make_pack_expansion (pattern);
+      t = make_pack_expansion (pattern, complain);
       PACK_EXPANSION_EXTRA_ARGS (t) = args;
       return t;
     }
@@ -11588,7 +11593,7 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
 			 /*integral_constant_expression_p=*/false);
       else
 	t = tsubst (pattern, args, complain, in_decl);
-      t = make_pack_expansion (t);
+      t = make_pack_expansion (t, complain);
       return t;
     }
 
@@ -21323,7 +21328,7 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict,
 	  if (REFERENCE_REF_P (arg))
 	    arg = TREE_OPERAND (arg, 0);
 	  if (pexp)
-	    arg = make_pack_expansion (arg);
+	    arg = make_pack_expansion (arg, complain);
 	  return unify (tparms, targs, TREE_OPERAND (parm, 0), arg,
 			strict, explain_p);
 	}

gcc/cp/tree.c

@@ -1208,7 +1208,7 @@ cp_build_qualified_type_real (tree type,
       tree t = PACK_EXPANSION_PATTERN (type);
 
       t = cp_build_qualified_type_real (t, type_quals, complain);
-      return make_pack_expansion (t);
+      return make_pack_expansion (t, complain);
     }
 
   /* A reference or method type shall not be cv-qualified.

gcc/testsuite/ChangeLog

+2017-11-02  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/81957
+	* g++.dg/cpp0x/variadic-crash5.C: New.
+
 2017-11-02  Steve Ellcey  <sellcey@cavium.com>
 
 	PR target/79868

gcc/testsuite/g++.dg/cpp0x/variadic-crash5.C

+// PR c++/81957
+// { dg-do compile { target c++11 } }
+
+template <class T, T v>
+struct integral_constant { };
+
+struct f {
+  template<bool b, typename Int>
+  void operator()(integral_constant<bool,b>, Int i) {
+  }
+};
+
+template<bool...Bs, typename F, typename ...T>
+auto dispatch(F f, T...t) -> decltype(f(integral_constant<bool,Bs>()..., t...)) {
+  return f(integral_constant<bool,Bs>()..., t...);
+}
+
+template<bool...Bs, typename F, typename ...T>
+auto dispatch(F f, bool b, T...t) -> decltype(dispatch<Bs..., true>(f, t...)) {
+  if (b)
+    return dispatch<Bs..., true>(f, t...);
+  else
+    return dispatch<Bs..., false>(f, t...);
+}
+
+int main() {
+  dispatch(f(), true, 5);
+}