From e87561aa2efec60efb48b79bbd49d147ddeb4f0e Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Sun, 23 May 2010 22:10:15 +0000
Subject: [PATCH] An identity conversion is better than any non-identity
 conversion. Fixes PR7095.

llvm-svn: 104476
---
 clang/lib/Sema/SemaOverload.cpp      |  9 +++++++++
 clang/lib/Sema/SemaOverload.h        |  6 ++++++
 clang/test/SemaCXX/overload-call.cpp | 14 ++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index abbf3933486c..6c64905561bf 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -2076,6 +2076,15 @@ compareStandardConversionSubsets(ASTContext &Context,
   ImplicitConversionSequence::CompareKind Result
     = ImplicitConversionSequence::Indistinguishable;
 
+  // the identity conversion sequence is considered to be a subsequence of 
+  // any non-identity conversion sequence
+  if (SCS1.ReferenceBinding == SCS2.ReferenceBinding) {
+    if (SCS1.isIdentityConversion() && !SCS2.isIdentityConversion())
+      return ImplicitConversionSequence::Better;
+    else if (!SCS1.isIdentityConversion() && SCS2.isIdentityConversion())
+      return ImplicitConversionSequence::Worse;
+  }
+    
   if (SCS1.Second != SCS2.Second) {
     if (SCS1.Second == ICK_Identity)
       Result = ImplicitConversionSequence::Better;
diff --git a/clang/lib/Sema/SemaOverload.h b/clang/lib/Sema/SemaOverload.h
index 8d261ddcbe8e..eb4fc6581796 100644
--- a/clang/lib/Sema/SemaOverload.h
+++ b/clang/lib/Sema/SemaOverload.h
@@ -177,6 +177,12 @@ namespace clang {
     }
 
     void setAsIdentityConversion();
+    
+    bool isIdentityConversion() const {
+      return First == ICK_Identity && Second == ICK_Identity && 
+             Third == ICK_Identity;
+    }
+    
     ImplicitConversionRank getRank() const;
     bool isPointerConversionToBool() const;
     bool isPointerConversionToVoidPointer(ASTContext& Context) const;
diff --git a/clang/test/SemaCXX/overload-call.cpp b/clang/test/SemaCXX/overload-call.cpp
index 79c74cec4947..9618ea22495f 100644
--- a/clang/test/SemaCXX/overload-call.cpp
+++ b/clang/test/SemaCXX/overload-call.cpp
@@ -430,3 +430,17 @@ namespace PR6177 {
 
   void g() { f(""); } // expected-error{{volatile lvalue reference to type 'bool const volatile' cannot bind to a value of unrelated type 'char const [1]'}}
 }
+
+namespace PR7095 {
+  struct X { };
+
+  struct Y {
+    operator const X*();
+
+  private:
+    operator X*();
+  };
+
+  void f(const X *);
+  void g(Y y) { f(y); }
+}