From f4217f862aa0f4ed0284c8a2036bde6286477346 Mon Sep 17 00:00:00 2001
From: Vedant Kumar <vsk@apple.com>
Date: Thu, 16 Feb 2017 01:20:00 +0000
Subject: [PATCH] [Sema] Add lvalue-to-rvalue cast in
 direct-list-initialization of enum

After r264564, we allowed direct-list-initialization of an enum from an
integral value in C++1z mode, so long as that value can convert to the
enum's underlying type.

In this kind of initialization, we need a lvalue-to-rvalue conversion
for the initializer value if it is not a rvalue. This lets us accept the
following code:

  enum class A : unsigned {};
  A foo(unsigned x) { return A{x}; }

Differential Revision: https://reviews.llvm.org/D29723

llvm-svn: 295266
---
 clang/lib/Sema/SemaInit.cpp                   |  2 +
 .../dcl.decl/dcl.init/dcl.init.list/p3.cpp    | 45 +++++++++++++------
 2 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index a455717c4d60..151b974b4109 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -3981,6 +3981,8 @@ static void TryListInitialization(Sema &S,
       ImplicitConversionSequence ICS;
       ICS.setStandard();
       ICS.Standard.setAsIdentityConversion();
+      if (!E->isRValue())
+        ICS.Standard.First = ICK_Lvalue_To_Rvalue;
       // If E is of a floating-point type, then the conversion is ill-formed
       // due to narrowing, but go through the motions in order to produce the
       // right diagnostic.
diff --git a/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p3.cpp b/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p3.cpp
index f381ed708f70..ade327485773 100644
--- a/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p3.cpp
+++ b/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p3.cpp
@@ -150,35 +150,44 @@ namespace cxx1z_direct_enum_init {
 
     void f(T);
     f(T{0});
+
+    char c;
+    auto t3 = T{c};
   }
 #if __cplusplus <= 201402L
-  // expected-error@-15 5{{cannot initialize}}
-  // expected-error@-15 5{{cannot initialize}}
-  // expected-error@-15 5{{cannot initialize}}
+  // expected-error@-18 5{{cannot initialize}}
+  // expected-error@-18 5{{cannot initialize}}
+  // expected-error@-18 5{{cannot initialize}}
   //
   //
-  // expected-error@-15 5{{cannot initialize}}
+  // expected-error@-18 5{{cannot initialize}}
   //
-  // expected-error@-15 5{{cannot initialize}}
+  // expected-error@-18 5{{cannot initialize}}
   //
-  // expected-error@-15 5{{cannot initialize}}
+  // expected-error@-18 5{{cannot initialize}}
   //
   //
-  // expected-error@-15 5{{cannot initialize}}
+  // expected-error@-18 5{{cannot initialize}}
+  //
+  //
+  // expected-error@-18 5{{cannot initialize}}
 #else
-  // expected-error@-29 {{cannot initialize}}
-  // expected-error@-29 {{cannot initialize}}
-  // expected-error@-29 {{cannot initialize}}
+  // expected-error@-35 {{cannot initialize}}
+  // expected-error@-35 {{cannot initialize}}
+  // expected-error@-35 {{cannot initialize}}
   //
   //
-  // expected-error@-29 {{cannot initialize}}
+  // expected-error@-35 {{cannot initialize}}
   //
-  // expected-error@-29 {{cannot initialize}}
+  // expected-error@-35 {{cannot initialize}}
   //
-  // expected-error@-29 {{cannot initialize}}
+  // expected-error@-35 {{cannot initialize}}
   //
   //
-  // expected-error@-29 {{cannot initialize}}
+  // expected-error@-35 {{cannot initialize}}
+  //
+  //
+  // expected-error@-35 {{cannot initialize}}
 #endif
 
   template<typename T> void bad() {
@@ -252,4 +261,12 @@ namespace cxx1z_direct_enum_init {
     (void)B{0.0}; // expected-error {{type 'double' cannot be narrowed}}
 #endif
   }
+
+#if __cplusplus > 201402L
+  enum class F : unsigned {};
+  F f1(unsigned x) { return F{x}; }
+  F f2(const unsigned x) { return F{x}; }
+  F f3(bool x) { return F{x}; }
+  F f4(const bool x) { return F{x}; }
+#endif
 }