https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96204
Bug ID: 96204
Summary: gcc complains about private member access in SFINAE
context
Product: gcc
Version: 10.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: lts-rudolph at gmx dot de
Target Milestone: ---
gcc complains with following error in the example code:
main.cpp:59:72: error: 'void Child::setAttr(int)' is private within this
context
59 | struct has_set_attr_method<T,
void_t<decltype(std::declval<T>().setAttr(1))>> {
|
~~~~~~~~~~~~~~~~~~~~~~~~~^~~
main.cpp:85:14: note: declared private here
85 | void setAttr(int x) {
| ^~~~~~~
main.cpp:59:72: error: 'void Child::setAttr(int)' is private within this
context
59 | struct has_set_attr_method<T,
void_t<decltype(std::declval<T>().setAttr(1))>> {
|
~~~~~~~~~~~~~~~~~~~~~~~~~^~~
main.cpp:85:14: note: declared private here
85 | void setAttr(int x) {
| ^~~~~~~
main.cpp:59:72: error: 'void Child::setAttr(int)' is private within this
context
59 | struct has_set_attr_method<T,
void_t<decltype(std::declval<T>().setAttr(1))>> {
|
~~~~~~~~~~~~~~~~~~~~~~~~~^~~
main.cpp:85:14: note: declared private here
85 | void setAttr(int x) {
Full code example:
---------------
template <typename, typename = void_t<>>
struct has_set_attr_method {
static constexpr bool value = false;
};
template <typename T>
struct has_set_attr_method<T, void_t<decltype(std::declval<T>().setAttr(1))>> {
static constexpr bool value = true;
};
struct Parent
{
public:
template<typename T>
static void create() {
auto obj = T::create();
if constexpr(has_set_attr_method<T>::value) {
cout << "has setAttr" << endl;
} else {
cout << "no setAttr" << endl;
}
}
};
struct Child : public Parent {
public:
friend class Parent;
static auto create() {
return Child();
}
private:
void setAttr(int x) {
}
};
int main(int argc, char const *argv[]) {
Parent::create<Child>();
return 0;
}
---------------
Interestingly the failure depends on "friend" declaration inside "Child".
