Hamza Sood reported Dec 05, 2016 at 06:19 PM

Using co_await inside a lambda expression causes you to lose any captured variables.

int testNumber = 3; auto testBlock = [testNumber]() -> concurrency::task<void> { auto picker = ref new Windows::Storage::Pickers::FileOpenPicker(); picker->FileTypeFilter->Append("*");

 {
     std::wstringstream stream;
     stream << "Before: " << testNumber << "\n";
     OutputDebugString(stream.str().c_str());
 }

 co_await picker->PickSingleFileAsync();

 {
     std::wstringstream stream;
     stream << "After: " << testNumber << "\n";
     OutputDebugString(stream.str().c_str());
 }

}; testBlock();

In the above code testNumber is captured by value, so you'd expect both the before and after logs to print the value 3. However the actual result is: "Before: 3" and "After: -858993460". i.e. after using co_await, the captured variable isn't usable.