Handle converting member pointers to bool.

llvm-svn: 89692

clang/include/clang/AST/Expr.h

@@ -1574,7 +1574,11 @@ public:
     CK_FloatingToIntegral,
     
     /// CK_FloatingCast - Casting between floating types of different size.
-    CK_FloatingCast
+    CK_FloatingCast,
+    
+    /// CK_MemberPointerToBoolean - Member pointer to boolean
+    CK_MemberPointerToBoolean
+
   };
 
 private:

clang/lib/AST/Expr.cpp

@@ -556,6 +556,8 @@ const char *CastExpr::getCastKindName() const {
     return "FloatingToIntegral";
   case CastExpr::CK_FloatingCast:
     return "FloatingCast";
+  case CastExpr::CK_MemberPointerToBoolean:
+    return "MemberPointerToBoolean";
   }
 
   assert(0 && "Unhandled cast kind!");

clang/lib/CodeGen/CGExprScalar.cpp

@@ -901,6 +901,35 @@ Value *ScalarExprEmitter::EmitCastExpr(const CastExpr *CE) {
     return Yay;
   }
 
+  case CastExpr::CK_MemberPointerToBoolean: {
+    const MemberPointerType* T = E->getType()->getAs<MemberPointerType>();
+    
+    if (T->getPointeeType()->isFunctionType()) {
+      // We have a member function pointer.
+      llvm::Value *Ptr = CGF.CreateTempAlloca(ConvertType(E->getType()));
+      
+      CGF.EmitAggExpr(E, Ptr, /*VolatileDest=*/false);
+      
+      // Get the pointer.
+      llvm::Value *FuncPtr = Builder.CreateStructGEP(Ptr, 0, "src.ptr");
+      FuncPtr = Builder.CreateLoad(FuncPtr);
+      
+      llvm::Value *IsNotNull = 
+        Builder.CreateICmpNE(FuncPtr,
+                             llvm::Constant::getNullValue(FuncPtr->getType()),
+                             "tobool");
+      
+      return IsNotNull;
+    }
+   
+    // We have a regular member pointer.
+    Value *Ptr = Visit(const_cast<Expr*>(E));
+    llvm::Value *IsNotNull = 
+      Builder.CreateICmpNE(Ptr, CGF.CGM.EmitNullConstant(E->getType()),
+                           "tobool");
+    return IsNotNull;
+  }
+      
   }
 
   // Handle cases where the source is an non-complex type.

clang/lib/Sema/SemaExprCXX.cpp

@@ -1359,9 +1359,14 @@ Sema::PerformImplicitConversion(Expr *&From, QualType ToType,
     ImpCastExprToType(From, ToType, Kind);
     break;
   }
-  case ICK_Boolean_Conversion:
-    ImpCastExprToType(From, Context.BoolTy, CastExpr::CK_Unknown);
+  case ICK_Boolean_Conversion: {
+    CastExpr::CastKind Kind = CastExpr::CK_Unknown;
+    if (FromType->isMemberPointerType())
+      Kind = CastExpr::CK_MemberPointerToBoolean;
+    
+    ImpCastExprToType(From, Context.BoolTy, Kind);
     break;
+  }
 
   case ICK_Derived_To_Base:
     if (CheckDerivedToBaseConversion(From->getType(), 

clang/test/CodeGenCXX/member-function-pointers.cpp

@@ -55,6 +55,10 @@ void f3(A *a, A &ar) {
   (ar.*pa)();
 }
 
+bool f4() {
+  return pa;
+}
+
 // PR5177
 namespace PR5177 {
   struct A {