How to Determine Type Completeness in C without a Universal Template?

Determining Type Completeness with a Custom Template

Incomplete types, while not fully defined, play a crucial role in C programming. However, determining whether a type is complete can be challenging, especially with the lack of a dedicated template like Boost's is_complete.

Proposed Solution

Although a universal solution that fully adheres to the One Definition Rule (ODR) may be elusive, a platform-specific approach has proven effective for Microsoft Visual C . As outlined by Alexey Malistov, the following template can be employed:

<code class="cpp">namespace
{
    template<class T, int discriminator>
    struct is_complete {  
      static T &amp; getT();   
      static char (&amp; pass(T))[2]; 
      static char pass(...);   
      static const bool value = sizeof(pass(getT()))==2;
    };
}</code>

Usage

To leverage this template, simply utilize the macro IS_COMPLETE(X), where X is the type in question. For instance:

<code class="cpp">#define IS_COMPLETE(X) is_complete<X,__COUNTER__>::value</code>

Caveat

It's crucial to note that the __COUNTER__ macro is not part of the C standard. Therefore, this solution may not be suitable for all compilers.

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