From 6850fafd27ba804d4d4ca8af404beed5574e3749 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Sun, 29 Apr 2012 08:24:44 +0000
Subject: [PATCH] PR9546, DR1268: A prvalue cannot be reinterpret_cast to an
 rvalue reference type. But a glvalue can be reinterpret_cast to either flavor
 of reference.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@155789 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaCast.cpp                                   | 7 +++----
 test/CXX/expr/expr.post/expr.reinterpret.cast/p1-0x.cpp | 7 +++++--
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp
index 54683e127e..a67d1dec59 100644
--- a/lib/Sema/SemaCast.cpp
+++ b/lib/Sema/SemaCast.cpp
@@ -1504,10 +1504,9 @@ static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
   }
 
   if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
-    bool LValue = DestTypeTmp->isLValueReferenceType();
-    if (LValue && !SrcExpr.get()->isLValue()) {
-      // Cannot cast non-lvalue to lvalue reference type. See the similar 
-      // comment in const_cast.
+    if (!SrcExpr.get()->isGLValue()) {
+      // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the
+      // similar comment in const_cast.
       msg = diag::err_bad_cxx_cast_rvalue;
       return TC_NotApplicable;
     }
diff --git a/test/CXX/expr/expr.post/expr.reinterpret.cast/p1-0x.cpp b/test/CXX/expr/expr.post/expr.reinterpret.cast/p1-0x.cpp
index 22892a63ab..212adc8c2b 100644
--- a/test/CXX/expr/expr.post/expr.reinterpret.cast/p1-0x.cpp
+++ b/test/CXX/expr/expr.post/expr.reinterpret.cast/p1-0x.cpp
@@ -10,7 +10,10 @@ template<typename T> T&& xvalue();
 void test_classification(char *ptr) {
   int (&fr0)(int) = reinterpret_cast<int (&&)(int)>(f);
   int &&ir0 = reinterpret_cast<int &&>(*ptr);
-  int &&ir1 = reinterpret_cast<int &&>(0);
-  int &&ir2 = reinterpret_cast<int &&>('a');
+  int &&ir1 = reinterpret_cast<int &&>(0); // expected-error {{rvalue to reference type}}
+  int &&ir2 = reinterpret_cast<int &&>('a'); // expected-error {{rvalue to reference type}}
   int &&ir3 = reinterpret_cast<int &&>(xvalue<char>());
+  // Per DR1268, reinterpret_cast can convert between lvalues and xvalues.
+  int &ir4 = reinterpret_cast<int &>(xvalue<char>());
+  int &&ir5 = reinterpret_cast<int &&>(*ptr);
 }
-- 
2.40.0