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Add informative compilation failure for method_adaptor failures #1127

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Merged
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Oct 12, 2017
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Add informative compilation failure for method_adaptor failures #1127

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5 changes: 5 additions & 0 deletions include/pybind11/detail/common.h
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Original file line number Diff line number Diff line change
Expand Up @@ -581,6 +581,11 @@ template <typename T, typename... Us> using deferred_t = typename deferred_type<
template <typename Base, typename Derived> using is_strict_base_of = bool_constant<
std::is_base_of<Base, Derived>::value && !std::is_same<Base, Derived>::value>;

/// Like is_base_of, but also requires that the base type is accessible (i.e. that a Derived pointer
/// can be converted to a Base pointer)
template <typename Base, typename Derived> using is_accessible_base_of = bool_constant<
std::is_base_of<Base, Derived>::value && std::is_convertible<Derived *, Base *>::value>;

template <template<typename...> class Base>
struct is_template_base_of_impl {
template <typename... Us> static std::true_type check(Base<Us...> *);
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12 changes: 10 additions & 2 deletions include/pybind11/pybind11.h
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Expand Up @@ -997,10 +997,18 @@ template <typename /*Derived*/, typename F>
auto method_adaptor(F &&f) -> decltype(std::forward<F>(f)) { return std::forward<F>(f); }

template <typename Derived, typename Return, typename Class, typename... Args>
auto method_adaptor(Return (Class::*pmf)(Args...)) -> Return (Derived::*)(Args...) { return pmf; }
auto method_adaptor(Return (Class::*pmf)(Args...)) -> Return (Derived::*)(Args...) {
static_assert(detail::is_accessible_base_of<Class, Derived>::value,
"Cannot bind an inaccessible base class method; use a lambda definition instead");
return pmf;
}

template <typename Derived, typename Return, typename Class, typename... Args>
auto method_adaptor(Return (Class::*pmf)(Args...) const) -> Return (Derived::*)(Args...) const { return pmf; }
auto method_adaptor(Return (Class::*pmf)(Args...) const) -> Return (Derived::*)(Args...) const {
static_assert(detail::is_accessible_base_of<Class, Derived>::value,
"Cannot bind an inaccessible base class method; use a lambda definition instead");
return pmf;
}

template <typename type_, typename... options>
class class_ : public detail::generic_type {
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