[Bug c++/78850] Parameter of returned generic lambda allegedly shadows parameter of free function

[miklcct at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78850

Michael Tsang <miklcct at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |miklcct at gmail dot com

--- Comment #1 from Michael Tsang <miklcct at gmail dot com> ---
I think the following is related to this, where the parameter of a returned
lambda is mis-interpreted as shadowing a local variable:

[michael@samsung-rv510 ~]$ cat fix.cpp
#include <iostream>

using std::cin;
using std::cout;

struct Factorial {
    template<class Function> unsigned long operator()(Function self, unsigned
long n) const {
        return n ? n * self(self, n - 1) : 1;
    }
};

template<class Function> auto y(Function f) {
    return [f](auto n) {
        return f(f, n);
    };
}

int main() {
    unsigned long n;
    cin >> n;
    cout << y(Factorial())(n) << '\n';
    return 0;
}
[michael@samsung-rv510 ~]$ g++ -Wshadow -std=c++14 fix.cpp -o fix
fix.cpp: In instantiation of 'y(Function)::<lambda(auto:1)> [with auto:1 = long
unsigned int; Function = Factorial]':
fix.cpp:21:29:   required from here
fix.cpp:13:22: warning: declaration of 'n' shadows a previous local [-Wshadow]
     return [f](auto n) {
                      ^
fix.cpp:19:19: note: shadowed declaration is here
     unsigned long n;
                   ^