From b5630dbadf9a2a06754194387d6b0fd9962a67f1 Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Mon, 22 May 2017 19:43:28 +0000
Subject: Vendor import of llvm trunk r303571:
 https://llvm.org/svn/llvm-project/llvm/trunk@303571

---
 include/llvm/IR/OperandTraits.h | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'include/llvm/IR/OperandTraits.h')

diff --git a/include/llvm/IR/OperandTraits.h b/include/llvm/IR/OperandTraits.h
index e97a8009ccc03..7b94283856b6d 100644
--- a/include/llvm/IR/OperandTraits.h
+++ b/include/llvm/IR/OperandTraits.h
@@ -30,6 +30,9 @@ namespace llvm {
 template <typename SubClass, unsigned ARITY>
 struct FixedNumOperandTraits {
   static Use *op_begin(SubClass* U) {
+    static_assert(
+        !std::is_polymorphic<SubClass>::value,
+        "adding virtual methods to subclasses of User breaks use lists");
     return reinterpret_cast<Use*>(U) - ARITY;
   }
   static Use *op_end(SubClass* U) {
@@ -65,6 +68,9 @@ struct OptionalOperandTraits : public FixedNumOperandTraits<SubClass, ARITY> {
 template <typename SubClass, unsigned MINARITY = 0>
 struct VariadicOperandTraits {
   static Use *op_begin(SubClass* U) {
+    static_assert(
+        !std::is_polymorphic<SubClass>::value,
+        "adding virtual methods to subclasses of User breaks use lists");
     return reinterpret_cast<Use*>(U) - static_cast<User*>(U)->getNumOperands();
   }
   static Use *op_end(SubClass* U) {
-- 
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