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POinheriting from a class template with a default argument
 

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    <p>I've created a class looking something like this. The key is that it's got a main template argument plus a template base class with a default. There is also a templated copy constructor...</p> <pre><code>struct default_base{}; template &lt;typename T, typename TBase=default_base&gt; class some_class : public TBase{ public: some_class(){} template &lt;typename U, typename UBase&gt; some_class(const some_class&lt;U,UBase&gt;&amp; u){ T t(U()); } }; int main(){ some_class&lt;int&gt; a; return 0; } </code></pre> <p>I'm getting this annoyingly vague compiler error, and haven't been able to spot my error...so my question is - what's really wrong? I'm using gcc 4.8.1.</p> <pre><code>g++ -O0 -g3 -Wall -c -fmessage-length=0 -o "src\\stuff.o" "..\\src\\stuff.cpp" ..\src\stuff.cpp: In constructor 'some_class&lt;T, TBase&gt;::some_class(const some_class&lt;U, UBase&gt;&amp;)': ..\src\stuff.cpp:87:10: error: default argument for template parameter for class enclosing 'T t(U (*)())' T t(U()); ^ ..\src\stuff.cpp: In function 'int main()': ..\src\stuff.cpp:104:16: error: wrong number of template arguments (1, should be 2) some_class&lt;int&gt; a; ^ ..\src\stuff.cpp:82:7: error: provided for 'template&lt;class T, class TBase&gt; class some_class' class some_class : public TBase{ ^ ..\src\stuff.cpp:104:19: error: invalid type in declaration before ';' token some_class&lt;int&gt; a; </code></pre> <p>Edit: Spot on answers, Cheers :-) Even if I still think it should compile... this compiles...</p> <pre><code>template &lt;typename T&gt; struct some_other_class{ some_other_class(){} template &lt;typename U&gt; some_other_class(){ T t(U()); } }; </code></pre>
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