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copied!<p>This is because of the generic binding facility in terms of which the C++11 Standard defines not only how a thread is started, but also how <code>std::bind</code> and <code>std::function</code> work.</p> <p>In fact, Paragraph 30.3.1.2/3 of the C++11 Standard specifies about the variadic constructor of class <code>std::thread</code>:</p> <blockquote> <p><code>template <class F, class ...Args> explicit thread(F&& f, Args&&... args);</code></p> <p><em>Effects</em>: Constructs an object of type thread. The new thread of execution executes <strong><code>INVOKE (DECAY_- COPY ( std::forward<F>(f)), DECAY_COPY (std::forward<Args>(args))...)</code></strong> with the calls to <code>DECAY_COPY</code> being evaluated in the constructing thread. Any return value from this invocation is ignored. [...]</p> </blockquote> <p>Ignoring what <code>DECAY_COPY</code> does (it is not relevant to the question), this is how Paragraph 20.8.2 defines the <code>INVOKE</code> pseudo-function:</p> <blockquote> <p>Define <strong>INVOKE (f, t1, t2, ..., tN)</strong> as follows:</p> <p>— (t1.*f)(t2, ..., tN) when f is a pointer to a member function of a class T and t1 is an object of type T or a reference to an object of type T or a reference to an object of a type derived from T;</p> <p>— ((*t1).*f)(t2, ..., tN) when f is a pointer to a member function of a class T and t1 is not one of the types described in the previous item;</p> <p>— t1.*f when N == 1 and f is a pointer to member data of a class T and t1 is an object of type T or a reference to an object of type T or a reference to an object of a type derived from T;</p> <p>— <strong>(*t1).*f when N == 1 and f is a pointer to member data of a class T and t1 is not one of the types described in the previous item;</strong></p> <p>— f(t1, t2, ..., tN) in all other cases.</p> </blockquote> <p>Now the question becomes: </p> <blockquote> <p>Why does the C++11 Standard defines the <code>INVOKE</code> facility that way?</p> </blockquote> <p>And the answer is <strong><a href="https://stackoverflow.com/questions/12638393/why-does-invoke-facility-in-the-c11-standard-refer-to-data-members">here</a></strong>.</p>

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