lambda function throwing error

Question

I am getting this error message when I build my code,

"a lambda that has been specified to have a void return type cannot return a value"

bool StockCheck::InStock(const Shop& shop) const
{
    return std::any_of(m_products, [&shop, this](const std::unique_ptr<SelectedProduct>& selected)
    {
        auto inStock = selected->ProductInStock(shop);
        return inStock != SelectedProduct::NOT_IN_STOCK && selected->GetProductInStock(code);
    });
}

I am using VS2010, is it a problem? This will work in VS2013?

It seems correct, did you try to specify return type -> bool as workaround ? — Jarod42
– Jarod42, Commented Jul 24, 2015 at 11:20

lisyarus · Accepted Answer · 2015-07-24 11:33:07Z

6

Problem is, that you have lambda with two lines and compiler cannot determine return type (so it's equal to void) in C++11. You can specify ret. type manually like

return std::any_of(m_products.begin(), m_products.end(),
[&shop, this](const std::unique_ptr<SelectedProduct>& selected) -> bool
{
    auto inStock = selected->ProductInStock(shop);
    return inStock != SelectedProduct::NOT_IN_STOCK && selected->GetProductInStock(code);
});

or write without variable inStock just in one line.

return std::any_of(m_products.begin(), m_products.end(),
[&shop, this](const std::unique_ptr<SelectedProduct>& selected)
{
    return selected->ProductInStock(shop) != SelectedProduct::NOT_IN_STOCK &&
    selected->GetProductInStock(code);
});

edited Jul 24, 2015 at 11:33

lisyarus

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answered Jul 24, 2015 at 11:22

ForEveR

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1 Comment

ForEveR Over a year ago

@LightnessRacesinOrbit cppreference.com says, that The return type is deduced from return statements as if for a function whose return type is declared auto. since C++14.

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