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POC++0x Error: overloading a function with std::shared_ptr to const argument is ambiguous
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  1. POC++0x Error: overloading a function with std::shared_ptr to const argument is ambiguous
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    copied!<p>Suppose I have two <strong>unrelated</strong> classes <code>A</code> and <code>B</code>. I also have a class <code>Bla</code> that uses <code>boost::shared_ptr</code> like this:</p> <pre><code>class Bla { public: void foo(boost::shared_ptr&lt;const A&gt;); void foo(boost::shared_ptr&lt;const B&gt;); } </code></pre> <p>Notice the <strong>const</strong>. That's the important part which the original version of this question lacked. This compiles, and the following code works:</p> <pre><code>Bla bla; boost::shared_ptr&lt;A&gt; a; bla.foo(a); </code></pre> <p>However, if I switch from using <code>boost::shared_ptr</code> to using <code>std::shared_ptr</code> in the above examples, I get a compilation error that says:</p> <pre><code>"error: call of overloaded 'foo(std::shared_ptr&lt;A&gt;)' is ambiguous note: candidates are: void foo(std::shared_ptr&lt;const A&gt;) void foo(std::shared_ptr&lt;const B&gt;) </code></pre> <p>Can you help me figure out why the compiler can't figure out which function to use in the std::shared_ptr case, and can in the boost::shared_ptr case? I'm using the default GCC and Boost versions from the Ubuntu 11.04 package repository which are currently GCC 4.5.2 and Boost 1.42.0.</p> <p>Here is the full code that you can try compiling:</p> <pre><code>#include &lt;boost/shared_ptr.hpp&gt; using boost::shared_ptr; // #include &lt;memory&gt; // using std::shared_ptr; class A {}; class B {}; class Bla { public: void foo(shared_ptr&lt;const A&gt;) {} void foo(shared_ptr&lt;const B&gt;) {} }; int main() { Bla bla; shared_ptr&lt;A&gt; a; bla.foo(a); return 0; } </code></pre> <p>By the way, this issue motivated me to ask <a href="https://stackoverflow.com/questions/6322245/should-i-switch-from-using-boostshared-ptr-to-stdshared-ptr">this question</a> about whether I should be using <code>std::shared_ptr</code> at all yet ;-)</p>
 

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