From 980fb16f9a05f946007cd65929bd611d8812d8cd Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Thu, 29 Apr 2010 18:24:40 +0000
Subject: When determining a standard conversion sequence involves resolving
 the address of an overloaded function (or function template), perform that
 resolution prior to determining the implicit conversion sequence. This
 resolution is not part of the implicit conversion sequence itself.

Previously, we would always consider this resolution to be a
function pointer decay, which was a lie: there might be an explicit &
in the expression, in which case decay should not occur. This caused
the CodeGen assertion in PR6973 (where we created a
pointer to a pointer to a function when we should have had a pointer
to a function), but it's likely that there are corner cases of
overload resolution where this would have failed.

Cleaned up the code involved in determining the type that will
produced afer resolving the overloaded function reference, and added
an assertion to make sure the result is correct. Fixes PR6973.

llvm-svn: 102650
---
 clang/lib/Sema/SemaOverload.cpp | 62 ++++++++++++++++++++---------------------
 1 file changed, 30 insertions(+), 32 deletions(-)

(limited to 'clang/lib/Sema/SemaOverload.cpp')

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 06b5fcb318c..2a2521a32c2 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -622,8 +622,36 @@ Sema::IsStandardConversion(Expr* From, QualType ToType,
   // array-to-pointer conversion, or function-to-pointer conversion
   // (C++ 4p1).
 
-  DeclAccessPair AccessPair;
-
+  if (FromType == Context.OverloadTy) {
+    DeclAccessPair AccessPair;
+    if (FunctionDecl *Fn
+          = ResolveAddressOfOverloadedFunction(From, ToType, false, 
+                                               AccessPair)) {
+      // We were able to resolve the address of the overloaded function,
+      // so we can convert to the type of that function.
+      FromType = Fn->getType();
+      if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn)) {
+        if (!Method->isStatic()) {
+          Type *ClassType 
+            = Context.getTypeDeclType(Method->getParent()).getTypePtr();
+          FromType = Context.getMemberPointerType(FromType, ClassType);
+        }
+      }
+      
+      // If the "from" expression takes the address of the overloaded
+      // function, update the type of the resulting expression accordingly.
+      if (FromType->getAs<FunctionType>())
+        if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(From->IgnoreParens()))
+          if (UnOp->getOpcode() == UnaryOperator::AddrOf)
+            FromType = Context.getPointerType(FromType);
+ 
+      // Check that we've computed the proper type after overload resolution.
+      assert(Context.hasSameType(FromType,
+              FixOverloadedFunctionReference(From, AccessPair, Fn)->getType()));
+    } else {
+      return false;
+    }
+  } 
   // Lvalue-to-rvalue conversion (C++ 4.1):
   //   An lvalue (3.10) of a non-function, non-array type T can be
   //   converted to an rvalue.
@@ -668,36 +696,6 @@ Sema::IsStandardConversion(Expr* From, QualType ToType,
     // type "pointer to T." The result is a pointer to the
     // function. (C++ 4.3p1).
     FromType = Context.getPointerType(FromType);
-  } else if (From->getType() == Context.OverloadTy) {
-    if (FunctionDecl *Fn
-          = ResolveAddressOfOverloadedFunction(From, ToType, false, 
-                                               AccessPair)) {
-      // Address of overloaded function (C++ [over.over]).
-      SCS.First = ICK_Function_To_Pointer;
-
-      // We were able to resolve the address of the overloaded function,
-      // so we can convert to the type of that function.
-      FromType = Fn->getType();
-      if (ToType->isLValueReferenceType())
-        FromType = Context.getLValueReferenceType(FromType);
-      else if (ToType->isRValueReferenceType())
-        FromType = Context.getRValueReferenceType(FromType);
-      else if (ToType->isMemberPointerType()) {
-        // Resolve address only succeeds if both sides are member pointers,
-        // but it doesn't have to be the same class. See DR 247.
-        // Note that this means that the type of &Derived::fn can be
-        // Ret (Base::*)(Args) if the fn overload actually found is from the
-        // base class, even if it was brought into the derived class via a
-        // using declaration. The standard isn't clear on this issue at all.
-        CXXMethodDecl *M = cast<CXXMethodDecl>(Fn);
-        FromType = Context.getMemberPointerType(FromType,
-                      Context.getTypeDeclType(M->getParent()).getTypePtr());
-      } else {
-        FromType = Context.getPointerType(FromType);
-      }
-    } else {
-      return false;
-    }
   } else {
     // We don't require any conversions for the first step.
     SCS.First = ICK_Identity;
-- 
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