How Can We View Compiler-Instantiated Template Code in C ?

Viewing Compiler-Instantiated Template Code in C

In C , template instantiation automatically generates specialized code for different template parameter types. To delve into the specifics of template instantiation, consider the following question:

Can we see the templates instantiated by the C compiler?

The answer to this inquiry lies in leveraging specific compiler options to expose the compiler-generated code. One such compiler is Clang, which offers the -Xclang -ast-print flag to achieve this functionality.

To illustrate this process, let's take the example provided in the original question:

<code class="cpp">template <class T> T add(T a, T b) {
    return a + b;
}</code>

When you call this template with specific parameters, such as add(10, 2), Clang can be directed to print the instantiated code as follows:

$ clang++ -Xclang -ast-print -fsyntax-only test.cpp

Here, test.cpp contains the template code along with a dummy function tmp() that invokes the template specialization.

The output produced by Clang provides a detailed view of the instantiated code:

template <class T> T add(T a, T b) {
    return a + b;
}
template<> int add<int>(int a, int b) {
    return a + b;
}
void tmp() {
    add<int>(10, 2);
}

This output clearly demonstrates how Clang generates a specialized version of the template function for the int type. By taking advantage of the -Xclang -ast-print option, you can gain valuable insights into the inner workings of template instantiation in C .

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