c++ - 如何避免本地 lambda 影子重载解析？

Question

这是通过 4 层间接寻址发生的事情的简化版本。覆盖分辨率在具有相同名称的本地 lambda 附近失效。这是某种维护问题，特别是如果代码仍然构建(这里没有构建)并且错误仅在测试中被捕获。

有没有一种优雅的方法来规避这种情况？查看Godbolt Playgound对于这个问题。

#include "catch.hpp"

#include <iostream>
#include <map>
#include <string>

namespace {

struct Something {};

template <typename T>
void process(const T& x, Something const& s){}

struct A {
};

void process(A const& p, Something const& s){}

struct B {
};

void process(B const& p, Something const& s){}
} // namespace

int main {
    struct C {};

    // THIS lanbda shadows the visibility of formerly defined
    // functions with same name. This is a maintainability issue
    auto process = [](C const& p, Something const& s) {};

    Something s{};

    A a{};
    B b{};
    C c{};

    process(a, s);
    process(b, s);
}

Answer 1

您可能会明确说明过载:

// C++17 implementation, might have similar code for C++11/C++14
template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;

然后:

auto process = overloaded{
    [](C const& p, Something const& s) {},
    [](const auto& p, Something const& s){::process(p, s);}
};

Demo