[cfe-dev] No warning when lambda returns reference to temporary

[Matthew Urquhart via cfe-dev]

Hiya,

I ran into this (presumably) undefined behaviour today, and wonder if it's
a bug or expected. My app was coded similarly and ran correctly on
macOS/LLVM version 8.1.0 (clang-802.0.38) but not
Ubuntu14.04/gcc-4.7.3-12ubuntu1

In the case of this code, it's invalid since the lambda returns a reference
to a temp object. My bad, I'll fix it. Seems the compiler could've warned
me though :)

Compiler warns when explicitly specifying the return type of the lambda
using `->` operator, but not when implicit. Is this expected or a bug?

Thanks in advance,
Matt

// Minimal test case:

#include <functional>

#include <iostream>


void print_stuff(std::function<const int&()> f) {

    std::cout << "stuff is: " << f() << std::endl;

}


int main(int argc, char *argv[]) {

    print_stuff([]() {

        int i = 123;

        return i;

    });

}
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