[cfe-dev] Template default arg : Friend function cannot access private member

[suyog sarda]

This is regarding a test case which involves default argument
deduction/substitution. The test case can be summarized as :


template <class T, class = typename T::I>h(T){}

template <class T, class = typename T::I>j(T){}

class A
{
typedef int I;
friend void h<A>(A);

};

int main()
{
A a;
h(a);
j(a);
}

gcc-4.8.1 throws error for function j, since it has been not been declared
friend nor it is private to class A and hence violates access rule for

private member I(which is valid). gcc does not throw error for function h
since it has been declared as friend to class A and hence can access

private member I.

Clang throws error for both the functions. Error for function j (not
declared friend is valid and as expected), but it throws error even for

friend function h (error : deduction of default arg failed since I is a
private member of class A). This violates the accessibility of the friend

function.

The standard says - (At 14.8.2 pt 8)


"If a substitution results in an invalid type or expression, type deduction
fails. An in valid type or expression

is one that would be ill-formed if written using the substituted arguments.
[ Note: Access checking is done as

part of the substitution process. —end note ]"


Can someone please provide inputs as to how to check where the access
rights are being checked in clang?  I am using QT creator to debug clang

-- 
With regards,
Suyog
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