Basic support for taking the address of an overloaded function
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59000 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index d7518e0..3b187f2 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -438,6 +438,10 @@
void PrintOverloadCandidates(OverloadCandidateSet& CandidateSet,
bool OnlyViable);
+ FunctionDecl *ResolveAddressOfOverloadedFunction(Expr *From, QualType ToType,
+ bool Complain);
+ void FixOverloadedFunctionReference(Expr *E, FunctionDecl *Fn);
+
/// Helpers for dealing with function parameters
bool CheckParmsForFunctionDef(FunctionDecl *FD);
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 3495880..2f43e5f 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -1529,6 +1529,22 @@
QualType T1 = DeclType->getAsReferenceType()->getPointeeType();
QualType T2 = Init->getType();
+ // If the initializer is the address of an overloaded function, try
+ // to resolve the overloaded function. If all goes well, T2 is the
+ // type of the resulting function.
+ if (T2->isOverloadType()) {
+ FunctionDecl *Fn = ResolveAddressOfOverloadedFunction(Init, DeclType,
+ ICS != 0);
+ if (Fn) {
+ // Since we're performing this reference-initialization for
+ // real, update the initializer with the resulting function.
+ if (!ICS)
+ FixOverloadedFunctionReference(Init, Fn);
+
+ T2 = Fn->getType();
+ }
+ }
+
// Compute some basic properties of the types and the initializer.
bool DerivedToBase = false;
Expr::isLvalueResult InitLvalue = Init->isLvalue(Context);
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 3bb7c09..a45d671 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -2511,6 +2511,8 @@
/// object cannot be declared with storage class register or be a bit field.
/// Note: The usual conversions are *not* applied to the operand of the &
/// operator (C99 6.3.2.1p[2-4]), and its result is never an lvalue.
+/// In C++, the operand might be an overloaded function name, in which case
+/// we allow the '&' but retain the overloaded-function type.
QualType Sema::CheckAddressOfOperand(Expr *op, SourceLocation OpLoc) {
if (getLangOptions().C99) {
// Implement C99-only parts of addressof rules.
@@ -2554,7 +2556,9 @@
std::string("register variable"), op->getSourceRange());
return QualType();
}
- } else
+ } else if (isa<OverloadedFunctionDecl>(dcl))
+ return Context.OverloadTy;
+ else
assert(0 && "Unknown/unexpected decl type");
}
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 41ee8dd..a6a62a9 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -280,7 +280,16 @@
break;
case ICK_Array_To_Pointer:
- FromType = Context.getArrayDecayedType(FromType);
+ if (FromType->isOverloadType()) {
+ FunctionDecl *Fn = ResolveAddressOfOverloadedFunction(From, ToType, true);
+ if (!Fn)
+ return true;
+
+ FixOverloadedFunctionReference(From, Fn);
+ FromType = From->getType();
+ } else {
+ FromType = Context.getArrayDecayedType(FromType);
+ }
ImpCastExprToType(From, FromType);
break;
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 176701e..b60e554 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -426,7 +426,8 @@
// converted to an rvalue.
Expr::isLvalueResult argIsLvalue = From->isLvalue(Context);
if (argIsLvalue == Expr::LV_Valid &&
- !FromType->isFunctionType() && !FromType->isArrayType()) {
+ !FromType->isFunctionType() && !FromType->isArrayType() &&
+ !FromType->isOverloadType()) {
SCS.First = ICK_Lvalue_To_Rvalue;
// If T is a non-class type, the type of the rvalue is the
@@ -465,9 +466,20 @@
// type "pointer to T." The result is a pointer to the
// function. (C++ 4.3p1).
FromType = Context.getPointerType(FromType);
-
- // FIXME: Deal with overloaded functions here (C++ 4.3p2).
}
+ // Address of overloaded function (C++ [over.over]).
+ else if (FunctionDecl *Fn
+ = ResolveAddressOfOverloadedFunction(From, ToType, false)) {
+ 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->isReferenceType())
+ FromType = Context.getReferenceType(FromType);
+ else
+ FromType = Context.getPointerType(FromType);
+ }
// We don't require any conversions for the first step.
else {
SCS.First = ICK_Identity;
@@ -1681,4 +1693,101 @@
}
}
+/// ResolveAddressOfOverloadedFunction - Try to resolve the address of
+/// an overloaded function (C++ [over.over]), where @p From is an
+/// expression with overloaded function type and @p ToType is the type
+/// we're trying to resolve to. For example:
+///
+/// @code
+/// int f(double);
+/// int f(int);
+///
+/// int (*pfd)(double) = f; // selects f(double)
+/// @endcode
+///
+/// This routine returns the resulting FunctionDecl if it could be
+/// resolved, and NULL otherwise. When @p Complain is true, this
+/// routine will emit diagnostics if there is an error.
+FunctionDecl *
+Sema::ResolveAddressOfOverloadedFunction(Expr *From, QualType ToType,
+ bool Complain) {
+ QualType FunctionType = ToType;
+ if (const PointerLikeType *ToTypePtr = ToType->getAsPointerLikeType())
+ FunctionType = ToTypePtr->getPointeeType();
+
+ // We only look at pointers or references to functions.
+ if (!FunctionType->isFunctionType())
+ return 0;
+
+ // Find the actual overloaded function declaration.
+ OverloadedFunctionDecl *Ovl = 0;
+
+ // C++ [over.over]p1:
+ // [...] [Note: any redundant set of parentheses surrounding the
+ // overloaded function name is ignored (5.1). ]
+ Expr *OvlExpr = From->IgnoreParens();
+
+ // C++ [over.over]p1:
+ // [...] The overloaded function name can be preceded by the &
+ // operator.
+ if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(OvlExpr)) {
+ if (UnOp->getOpcode() == UnaryOperator::AddrOf)
+ OvlExpr = UnOp->getSubExpr()->IgnoreParens();
+ }
+
+ // Try to dig out the overloaded function.
+ if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(OvlExpr))
+ Ovl = dyn_cast<OverloadedFunctionDecl>(DR->getDecl());
+
+ // If there's no overloaded function declaration, we're done.
+ if (!Ovl)
+ return 0;
+
+ // Look through all of the overloaded functions, searching for one
+ // whose type matches exactly.
+ // FIXME: When templates or using declarations come along, we'll actually
+ // have to deal with duplicates, partial ordering, etc. For now, we
+ // can just do a simple search.
+ FunctionType = Context.getCanonicalType(FunctionType.getUnqualifiedType());
+ for (OverloadedFunctionDecl::function_iterator Fun = Ovl->function_begin();
+ Fun != Ovl->function_end(); ++Fun) {
+ // C++ [over.over]p3:
+ // Non-member functions and static member functions match
+ // targets of type “pointer-to-function”or
+ // “reference-to-function.”
+ if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(*Fun))
+ if (!Method->isStatic())
+ continue;
+
+ if (FunctionType == Context.getCanonicalType((*Fun)->getType()))
+ return *Fun;
+ }
+
+ return 0;
+}
+
+/// FixOverloadedFunctionReference - E is an expression that refers to
+/// a C++ overloaded function (possibly with some parentheses and
+/// perhaps a '&' around it). We have resolved the overloaded function
+/// to the function declaration Fn, so patch up the expression E to
+/// refer (possibly indirectly) to Fn.
+void Sema::FixOverloadedFunctionReference(Expr *E, FunctionDecl *Fn) {
+ if (ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
+ FixOverloadedFunctionReference(PE->getSubExpr(), Fn);
+ E->setType(PE->getSubExpr()->getType());
+ } else if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(E)) {
+ assert(UnOp->getOpcode() == UnaryOperator::AddrOf &&
+ "Can only take the address of an overloaded function");
+ FixOverloadedFunctionReference(UnOp->getSubExpr(), Fn);
+ E->setType(Context.getPointerType(E->getType()));
+ } else if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E)) {
+ assert(isa<OverloadedFunctionDecl>(DR->getDecl()) &&
+ "Expected overloaded function");
+ DR->setDecl(Fn);
+ E->setType(Fn->getType());
+ } else {
+ assert(false && "Invalid reference to overloaded function");
+ }
+}
+
} // end namespace clang