/// \brief Figure out if an expression could be turned into a call.
///
/// Use this when trying to recover from an error where the programmer may have
/// written just the name of a function instead of actually calling it.
///
/// \param E - The expression to examine.
/// \param ZeroArgCallReturnTy - If the expression can be turned into a call
/// with no arguments, this parameter is set to the type returned by such a
/// call; otherwise, it is set to an empty QualType.
/// \param NonTemplateOverloads - If the expression is an overloaded function
/// name, this parameter is populated with the decls of the various overloads.
bool Sema::isExprCallable(const Expr &E, QualType &ZeroArgCallReturnTy,
UnresolvedSetImpl &NonTemplateOverloads) {
ZeroArgCallReturnTy = QualType();
NonTemplateOverloads.clear();
if (const OverloadExpr *Overloads = dyn_cast<OverloadExpr>(&E)) {
for (OverloadExpr::decls_iterator it = Overloads->decls_begin(),
DeclsEnd = Overloads->decls_end(); it != DeclsEnd; ++it) {
// Our overload set may include TemplateDecls, which we'll ignore for our
// present purpose.
if (const FunctionDecl *OverloadDecl = dyn_cast<FunctionDecl>(*it)) {
NonTemplateOverloads.addDecl(*it);
if (OverloadDecl->getMinRequiredArguments() == 0)
ZeroArgCallReturnTy = OverloadDecl->getResultType();
}
}
return true;
}
if (const DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(&E)) {
if (const FunctionDecl *Fun = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
if (Fun->getMinRequiredArguments() == 0)
ZeroArgCallReturnTy = Fun->getResultType();
return true;
}
}
// We don't have an expression that's convenient to get a FunctionDecl from,
// but we can at least check if the type is "function of 0 arguments".
QualType ExprTy = E.getType();
const FunctionType *FunTy = NULL;
QualType PointeeTy = ExprTy->getPointeeType();
if (!PointeeTy.isNull())
FunTy = PointeeTy->getAs<FunctionType>();
if (!FunTy)
FunTy = ExprTy->getAs<FunctionType>();
if (!FunTy && ExprTy == Context.BoundMemberTy) {
// Look for the bound-member type. If it's still overloaded, give up,
// although we probably should have fallen into the OverloadExpr case above
// if we actually have an overloaded bound member.
QualType BoundMemberTy = Expr::findBoundMemberType(&E);
if (!BoundMemberTy.isNull())
FunTy = BoundMemberTy->castAs<FunctionType>();
}
if (const FunctionProtoType *FPT =
dyn_cast_or_null<FunctionProtoType>(FunTy)) {
if (FPT->getNumArgs() == 0)
ZeroArgCallReturnTy = FunTy->getResultType();
return true;
}
return false;
}
/// \brief Figure out if an expression could be turned into a call.
///
/// Use this when trying to recover from an error where the programmer may have
/// written just the name of a function instead of actually calling it.
///
/// \param E - The expression to examine.
/// \param ZeroArgCallReturnTy - If the expression can be turned into a call
/// with no arguments, this parameter is set to the type returned by such a
/// call; otherwise, it is set to an empty QualType.
/// \param OverloadSet - If the expression is an overloaded function
/// name, this parameter is populated with the decls of the various overloads.
bool Sema::isExprCallable(const Expr &E, QualType &ZeroArgCallReturnTy,
UnresolvedSetImpl &OverloadSet) {
ZeroArgCallReturnTy = QualType();
OverloadSet.clear();
if (E.getType() == Context.OverloadTy) {
OverloadExpr::FindResult FR = OverloadExpr::find(const_cast<Expr*>(&E));
const OverloadExpr *Overloads = FR.Expression;
for (OverloadExpr::decls_iterator it = Overloads->decls_begin(),
DeclsEnd = Overloads->decls_end(); it != DeclsEnd; ++it) {
OverloadSet.addDecl(*it);
// Check whether the function is a non-template which takes no
// arguments.
if (const FunctionDecl *OverloadDecl
= dyn_cast<FunctionDecl>((*it)->getUnderlyingDecl())) {
if (OverloadDecl->getMinRequiredArguments() == 0)
ZeroArgCallReturnTy = OverloadDecl->getResultType();
}
}
// Ignore overloads that are pointer-to-member constants.
if (FR.HasFormOfMemberPointer)
return false;
return true;
}
if (const DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E.IgnoreParens())) {
if (const FunctionDecl *Fun = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
if (Fun->getMinRequiredArguments() == 0)
ZeroArgCallReturnTy = Fun->getResultType();
return true;
}
}
// We don't have an expression that's convenient to get a FunctionDecl from,
// but we can at least check if the type is "function of 0 arguments".
QualType ExprTy = E.getType();
const FunctionType *FunTy = NULL;
QualType PointeeTy = ExprTy->getPointeeType();
if (!PointeeTy.isNull())
FunTy = PointeeTy->getAs<FunctionType>();
if (!FunTy)
FunTy = ExprTy->getAs<FunctionType>();
if (!FunTy && ExprTy == Context.BoundMemberTy) {
// Look for the bound-member type. If it's still overloaded, give up,
// although we probably should have fallen into the OverloadExpr case above
// if we actually have an overloaded bound member.
QualType BoundMemberTy = Expr::findBoundMemberType(&E);
if (!BoundMemberTy.isNull())
FunTy = BoundMemberTy->castAs<FunctionType>();
}
if (const FunctionProtoType *FPT =
dyn_cast_or_null<FunctionProtoType>(FunTy)) {
if (FPT->getNumArgs() == 0)
ZeroArgCallReturnTy = FunTy->getResultType();
return true;
}
return false;
}
