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POinvalid initialization of non-const reference of type in gcc but not Visual Studio
 

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  1. POinvalid initialization of non-const reference of type in gcc but not Visual Studio
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    <p>I have some code where IInterface is an abstract class.</p> <p>I was writing this </p> <pre><code>IInterface &amp;q = InterfaceImpl(); </code></pre> <p>and compiled it in Visual Studio 2008 and it worked fine. Then I ported it to a gcc project and suddenly I got this error:</p> <pre><code>error: invalid initialization of non-const reference of type 'IInterface&amp;' from a temporary of type 'InterfaceImpl' </code></pre> <p>When trying to find out what is wrong I found this thread <a href="https://stackoverflow.com/questions/8293426/error-invalid-initialization-of-non-const-reference-of-type-int-from-an-rval">error: invalid initialization of non-const reference of type ‘int&amp;’ from an rvalue of type ‘int’</a> and at least understand now what is wrong. So changing it to this:</p> <pre><code>InterfaceImpl i = InterfaceImpl(); IInterface &amp;q = i; </code></pre> <p>made it compile:</p> <p>However, The lifetime of these two objects are the same, so I don't really understand why gcc can not create a temporary object as apparently MS did. I assume that this is defined by the standard? When I look at the link above, I can understand why it makes no sense with something like a base type, but why does it need to get an error in case of an object?</p> <p>I also tried it like this, but then I get the error that IInterface is an abstract class and can not be instantiated.</p> <pre><code>IInterface i = InterfaceImpl(); </code></pre> <p><code>i</code> should be initialized, not instantiated. Does this mean I would need a copy constructor or assignment operator in InterfaceImpl to make this work or why do I get this error? </p>
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    1. USDevolus
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    1. COThe standard states that you can only bind a temporary object to a const reference. MSVC's behaviour is non-standard.
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    2. CONot directly related to your question, but how about just using `InterfaceImpl q;`?
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      1. USVaughn Cato
    3. COI don't want to use it directly, because this is a simplified version of my project, to develop this part of it, without the overhead of recompiling everything until I know how this should work.The code above would't exist in the real project like this, I just happened to find this issue because of it.
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