Wow, what compiler is that? I would have expected a compiler warning for the unused function (and the unused variable) 
Sometimes c++ is strange. Just fell for { Pinger ping; PingController pc(Pinger); } wondering why pc's constructor never was called. Turns out, compilers aggressively interpret everything smelling like a function definition – in this case pc – as one, without warning.
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There is no unused variable, and the function is only declared, never defined. It's standard clang.
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But what about 'ping', isn't that a instance of type Pinger that is unused until it is out of scope?
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This is just a boiled down version of the problem. In the original code, ping was used later
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Arrggghh, OK... Coding reality sucks
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Took me a minute
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Took me two hours.
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But you did not have the hints you gave. I know these days. They feel so very productive. Not.
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In-body function declarations are indeed an odd artifact. One reason why we should move to auto-style variable declations in post-C++11 code: auto pc = PingController{Pinger};
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Yeah, curly braces helped me finally debug it. Will now use them everywhere where 11 is acceptable.
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I still don't get it. What I would expect is that "Pinger" in the second line is interpreted as a constructor. So a temporal object is passed to pc instead of the intended "ping" object. If accessed via "&", the compiler would warn. Not if just a function is called.
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But it isn't. Compiler thinks it's a function declaration for a function taking a (unnamed) Pinger object returning a PingerController object, called pc
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Ok, I got your point, thanks for the explanation. I have to try this with some compilers tomorrow.
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What did you expect to happen? Shirley you wanted to pass ping to the constructor, not Pinger?
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Yes. And I expect the compiler to at least warn me that an unused function declaration inside a function might not be what I intended. From c++11 I would be able to use "PingerController pc{Pinger};" which would have helped find the brain fart quicker.
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Yes, a warning would be good. The “if it could be a function declaration then it is” has been there since the earliest days of C++ or even C-with-classes — ever since constructors with arguments were invented.
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That‘s one of the first things every C++ developer learns: https://en.m.wikipedia.org/wiki/Most_vexing_parse …
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You was faster: I was searching for a nice uniform initialization explanation ;-)
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Thus ist why since C++-11 it IS reccomended to call the c-tors via curly braces. Like: PingController pc{Pinger};
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