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POincorrect result for std::is_trivially_constructible<T, T&>::value when T declared T::T(T&)
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  1. POincorrect result for std::is_trivially_constructible<T, T&>::value when T declared T::T(T&)
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    copied!<p>This is a little problem that I get confused with, I don't know how to describe it, so just see the codes below:</p> <pre><code>struct B { B() {} B(B&amp;) { std::cout &lt;&lt; "not trivial\n"; } }; int main() { B b1; B b2(b1); std::cout &lt;&lt; std::is_trivially_constructible&lt;B, B&amp;&gt;::value &lt;&lt; '\n'; return 0; } </code></pre> <p>the output is:</p> <pre><code>not trivial 1 </code></pre> <p>I'm using VS11.</p> <p><strong>EDIT:</strong></p> <p>I just tested the example in <a href="http://en.cppreference.com/w/cpp/types/is_constructible" rel="nofollow">http://en.cppreference.com/w/cpp/types/is_constructible</a> some of the output is incorrect.</p> <pre><code>#include &lt;iostream&gt; #include &lt;type_traits&gt; class Foo { int v1; double v2; public: Foo(int n) : v1(n), v2() {} Foo(int n, double f) : v1(n), v2(f) {} }; int main() { std::cout &lt;&lt; "Foo is ...\n" &lt;&lt; std::boolalpha &lt;&lt; "\tTrivially-constructible from const Foo&amp;? " &lt;&lt; std::is_trivially_constructible&lt;Foo, const Foo&amp;&gt;::value &lt;&lt; '\n' &lt;&lt; "\tTrivially-constructible from int? " &lt;&lt; std::is_trivially_constructible&lt;Foo, int&gt;::value &lt;&lt; '\n' &lt;&lt; "\tConstructible from int? " &lt;&lt; std::is_constructible&lt;Foo, int&gt;::value &lt;&lt; '\n' } </code></pre> <p>the output is:</p> <pre><code>Foo is ... Trivially-constructible from const Foo&amp;? true Trivially-constructible from int? true//Trivially-constructible from int? false Constructible from int? true Press any key to continue . . . </code></pre>
 

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