re PR c++/85258 (ICE with invalid range-based for-loop)

	PR c++/85258
	* constexpr.c (reduced_constant_expression_p): Return false for null
	trees.

	* g++.dg/parse/error61.C: New test.

From-SVN: r259355

gcc/cp/ChangeLog

+2018-04-12  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/85258
+	* constexpr.c (reduced_constant_expression_p): Return false for null
+	trees.
+
 2018-04-11  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/85032

gcc/cp/constexpr.c

@@ -1773,6 +1773,9 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
 bool
 reduced_constant_expression_p (tree t)
 {
+  if (t == NULL_TREE)
+    return false;
+
   switch (TREE_CODE (t))
     {
     case PTRMEM_CST:
@@ -1794,9 +1797,8 @@ reduced_constant_expression_p (tree t)
 	field = NULL_TREE;
       FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (t), i, idx, val)
 	{
-	  if (!val)
-	    /* We're in the middle of initializing this element.  */
-	    return false;
+	  /* If VAL is null, we're in the middle of initializing this
+	     element.  */
 	  if (!reduced_constant_expression_p (val))
 	    return false;
 	  if (field)

gcc/testsuite/ChangeLog

+2018-04-12  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/85258
+	* g++.dg/parse/error61.C: New test.
+
 2018-04-12  Cesar Philippidis  <cesar@codesourcery.com>
 
 	* testsuite/libgomp.oacc-c-c++-common/pr84955.c: Revert 259346.

gcc/testsuite/g++.dg/parse/error61.C

+// PR c++/85258
+// { dg-do compile { target c++11 } }
+
+template<int> void foo()
+{
+  int x[8];
+  for (int& i, j : x) // { dg-error "multiple" }
+    i = 0; // { dg-error "local variable" }
+}
+
+void bar()
+{
+  foo<0>();
+}