Does C Allow Partial Specialization of Function Templates?

Partial Specialization Anomaly: Uncovering Function Template Overload

In the realm of C programming, function template partial specialization is generally prohibited, allowing only full specializations. However, an interesting observation has emerged concerning a snippet of code that may appear to suggest otherwise.

Consider the following code:

#include <iostream>
using std::cin;
using std::cout;
using std::endl;

template <typename T1, typename T2>
inline T1 max(T1 const& a, T2 const& b) {
    return a < b ? b : a;
}

template <typename T>
inline T const& max(T const& a, T const& b) {
    return 10;
}

int main() {
    cout << max(4, 4.2) << endl;
    cout << max(5, 5) << endl;
    int z;
    cin >> z;
}

At first glance, it appears that the second max function template is a partial specialization of the first one, as both its template parameters represent the same type T. However, this assumption is incorrect.

In reality, this code is demonstrating function template overload, not partial specialization. Function template overload allows multiple function templates with the same name but different parameter types. In this case, the two max function templates have distinct signatures: one takes arguments of different types, while the other takes arguments of the same type.

Partial specialization, on the other hand, would require defining a specific version of the max function template for a particular set of template arguments, such as max. As per the C standard, this is not permitted for function templates.

It's important to note that some compilers may offer extensions that allow partial specialization of function templates. However, these extensions result in code that is not portable across all compilers and platforms.

Therefore, it's crucial to understand the distinction between function template overload and partial specialization to ensure code correctness and portability in C development.

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