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    <p>Here's a SFINAE-based solution that checks if a function-call expression yields an lvalue:</p> <pre><code>#include &lt;boost/type_traits.hpp&gt; #include &lt;boost/utility.hpp&gt; #include &lt;cstddef&gt; // Func: function (object/pointer/reference) type // Arg0: type of the first argument to use (for overload resolution) template&lt;class Func, class Arg0&gt; struct yields_lvalue_1 // with one argument { typedef char yes[1]; typedef char no[2]; // decay possible function types typedef typename boost::decay&lt;Func&gt;::type F_decayed; // a type whose constructor can take any lvalue expression struct Any { template&lt;class T&gt; Any(T&amp;); }; // SFINAE-test: if `Any(....)` is well-formed, this overload of `test` is // viable template&lt;class T&gt; static yes&amp; test(boost::integral_constant&lt;std::size_t, sizeof(Any( boost::declval&lt;T&gt;()(boost::declval&lt;Arg0&gt;()) ))&gt;*); // fall-back template&lt;class T&gt; static no&amp; test(...); // perform test static bool const result = sizeof(test&lt;F_decayed&gt;(0)) == sizeof(yes); }; </code></pre> <p>Some exemplary function objects:</p> <pre><code>struct foo { bool&amp; operator()(int); bool operator()(double); }; struct bar { template&lt;class T&gt; double operator()(T); }; </code></pre> <p>Usage example:</p> <pre><code>#include &lt;iostream&gt; #include &lt;iomanip&gt; void print(bool expect, bool result) { std::cout &lt;&lt; "expect: "&lt;&lt;std::setw(5)&lt;&lt;expect&lt;&lt;" -- result: "&lt;&lt;result&lt;&lt;"\n"; } int main() { std::cout &lt;&lt; std::boolalpha; print(true , yields_lvalue_1&lt;foo, int&gt; ::result); print(false, yields_lvalue_1&lt;foo, double&gt;::result); print(false, yields_lvalue_1&lt;bar, int&gt; ::result); print(true , yields_lvalue_1&lt;foo&amp;(*)(long), int&gt;::result); print(false, yields_lvalue_1&lt;void(*)(int), short&gt;::result); print(true , yields_lvalue_1&lt;bool&amp;(short), long&gt;::result); print(false, yields_lvalue_1&lt;void(float), int&gt;::result); print(true , yields_lvalue_1&lt;char&amp;(&amp;)(bool), long&gt;::result); print(false, yields_lvalue_1&lt;foo(&amp;)(int), short&gt;::result); } </code></pre>
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    1. POHow to determine if a function returns a reference in C++03?
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    1. USdyp
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    1. COInterestingly, your solution gives me different results in Visual C++ and Clang... try running my `Test` example with `yields_lvalue_1<Test, Test *>::result`.
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